Gen. Maxwell D. Taylor, a daring pioneer commander of airborne troops who became a major force in determining American military and diplomatic strategy from World War II through the Vietnam War and beyond, died Sunday night at Walter Reed Army Hospital in Washington. He was 85 years old.

As a special emissary to South Vietnam for President Kennedy and as President Johnson's Ambassador to South Vietnam during the American military buildup there, General Taylor was one of the most influential figures in the American military and diplomatic presence in Southeast Asia.

In the 1950's, when much of the military establishment favored nuclear strikes as the main line of strategic defense, he spoke out repeatedly in favor of a more flexible response and became one of the main architects of the modern army. It was his belief that the infantryman was indispensable in the atomic age, especially for fighting small-scale conflicts. Influenced Kennedy Campaign

The general's views, articulated in his best-selling book ''The Uncertain Trumpet,'' influenced Senator John F. Kennedy, who used some of the general's arguments in his 1960 Presidential campaign and, as President, turned to General Taylor for advice.

General Taylor headed a mission to South Vietnam in 1961 to determine the Communist threat to that country, made recommendations on the possible deployment of American troops in the conflict - and thus may have played a fateful role in increasing United States participation in the war.

At other times in his career, General Taylor was a decorated battlefield commander, commandant of West Point and American military commander in Berlin. He led American and United Nations forces in the Korean War and, before his final retirement, as Chairman of the Joint Chiefs of Staff under President Kennedy.

In announcing his death yesterday, the Pentagon said General Taylor had been admitted to the hospital in mid-January. An Army spokesman, Maj. Bruce Bell, reported that he died at 9:55 P.M. Sunday of amyotrophic lateral sclerosis, a degenerative disease of the nerve cells that is better known as Lou Gehrig's disease. Tributes Are Expressed

Secretary of Defense Caspar W. Weinberger declared, ''Throughout his life, General Taylor epitomized what it means to be a soldier, a diplomat and a scholar.'' He said he would be remembered as ''one of the great military men in American history.''

''America has lost one of the greatest soldier-statesmen in its history, and the Kennedy family has lost one of our closest and dearest friends,'' Senator Edward M. Kennedy said yesterday.

''General Taylor was that rare and gifted military leader in the nuclear age who also understood the importance of nuclear arms control. As chairman of the Joint Chiefs of Staff, his support made the Nuclear Test Ban Treaty of 1963 possible,'' the Massachusetts Democrat said.

''To President Kennedy, that treaty was the finest achievement of his Administration, the first step back from the nuclear brink, and it could not have happened without Maxwell Taylor. We shall miss his courage, his leadership and his friendship.'' Jumping Into Normandy

The tall, ramrod-straight general was a hero in the invasion of Sicily and Italy and, when he parachuted with the 101st Airborne Division into Normandy on D-Day in June 1944, he became the first American general to go into battle on French soil. He was a major figure in the winning of the Battle of the Bulge.

General Taylor might as easily have pursued an academic career. He had been a top honors graduate of West Point and later taught languages there. Fluent in several languages, he was as familiar with Virgil and Polybius as he was with Caesar and Clausewitz.

It was typical of the general, for example, to quote Polybius, a Greek historian of the pre-Christian era, when he testified before a Congressional committee in 1966 on the principle that guided the American bombing of North Vietnam: ''It is not the purpose of war to annihilate those who provoke it, but to cause them to mend their ways.''

Born Aug. 26, 1901, in Keynesville, a small town in north-central Missouri, Maxwell Davenport Taylor was the only child of John Earle and Pearle Davenport Taylor. His father was a lawyer for a railroad. Young Maxwell was much influenced by the Civil War tales of his maternal grandfather, who fought for the Confederacy. When he was 5 years old, he wrote years later, he decided he wanted to go to West Point. He was an active debater at Northeast High School in Kansas City, graduated at age 15, and went on to Kansas City Junior College.

While there, he took the entrance examinations for both the United States Military Academy and the Naval Academy. Although the future general had always excelled in such studies as Latin, Greek and Spanish, his knowledge of geography was so limited that he failed the Annapolis examination. Why He Wasn't an Admiral

''If the Strait of Malacca had been in Europe, I might have wound up an admiral instead of a general,'' General Taylor said years later.

At West Point he was a cadet captain, editor of the student newspaper and in 1922 graduated as the youngest cadet, fourth from the top of his class academically. As a second lieutenant in the Corps of Engineers, he attended the Engineers School in Virginia for a year before being assigned to duty in Maryland, Hawaii, and Washington state.

In the years after World War I, while the United States was all but disarmed militarily, advancement was slow in the regular Army. Lieutenant Taylor, who had transferred to the 10th Field Artillery in 1926, did not win his captain's bars until 1935.

Before that, marked as a bright young officer, he had been assigned to Paris to perfect his French, and on his return was sent to West Point to teach French and Spanish. He also attended the Army's Field Artillery School and, after a two-year course at the Command and General Staff School at Fort Leavenworth, Kan., was posted to the United States Embassy in Tokyo to learn Japanese. In 1939 he served as an assistant military attache in Beijing. An Accidental Paratrooper

After a course at the Army War College in June 1940, Major Taylor accompanied Gen. Matthew B. Ridgway on an inspection of defense forces in nine Latin American countries, and then took command of a field artillery battalion. By the time World War II broke out, he was chief of staff to General Ridgway, then commander of the 82d Infantry Division, which had been chosen as the nucleus of the Army's first two airborne divisions.

''I thus became a paratrooper almost entirely by accident,'' said General Taylor, who was promoted from colonel to brigadier general in December 1942, made artillery commander of the 82d Airborne, and shipped out with his division in March 1943. The 82d trained in Morocco before joining the invasion of Sicily and Italy in July 1943.

Much of General Taylor's future military career was to hinge on a daring act in the fall of 1943, when he volunteered for what has been called one of the most dangerous missions of the war.

Marshal Pietro Badoglio had just secretly surrendered the Italian forces to the Allies, but a strong anti-Badoglio faction of Italians still controlled Rome, and the city was cordoned by German troops. An Allied airborne invasion of Rome was considered, to coincide with the Badoglio surrender announcement. Gen. Walter Bedell Smith, chief of staff to Gen. Dwight D. Eisenhower, the Allied Commander, needed a high-ranking emissary to slip into Rome and determine the feasibility and necessity of an airborne landing. Warned of Risks

General Taylor and Col. William Tudor Gardner of the Army Air Corps landed in a small boat at night at the Italian port of Gaeta, where they were met by frightened Badoglio agents who warned them that, should partisans of either side discover them on Italian soil, they could be stood against a wall and shot. The American officers drove into Rome through enemy lines, going only so far as to remove their military caps to conceal their identities.

Finding that the Italians were not strong enough to root out the Germans in and around the city, General Taylor used his radio to call off the Allied airborne attack and avoid the almost certain loss of hundreds of his men's lives.

General Eisenhower later wrote of General Taylor: ''The risks he ran were greater than I asked any other agent or emmisary to take during the war - he carried weighty responsibilities and discharged them with unerring judgment and every minute was in imminent danger of discovery.''

The Rome mission won General Taylor a Silver Star and, a few months later, command of the 101st Airborne Division and promotion to major general. After he parachuted with his troops into Normandy, he won a Distinguished Service Cross and the nickname ''Mr. Attack.'' Led Invasion of Netherlands

After 33 days of intensive battle in France, General Taylor took his division back to England, where the 101st was attached to the First Allied Airborne Army. On Sept. 17, 1944, he led the 101st in the airborne army's invasion of the Netherlands and, in 73 days of hard fighting, suffered a minor wound.

Called to Washington on a special mission, he was not present at Bastogne, Belgium, when the Germans launched an overwhelming last-ditch offensive, the Battle of the Bulge, in the Ardennes forest in December 1944. As the 101st heroically held out against intensive attacks, General Taylor rushed back to the front to assist in the drive to relieve Bastogne, which was accomplished by Gen. George S. Patton's Third Army in January 1945.

Then it was back to West Point. In September 1945, General Taylor was installed as the 37th superintendent of the Military Academy. At 44, he was the youngest superintendent since Gen. Douglas MacArthur, who assumed the post in 1919 when he was 39.

General Taylor was credited with completely overhauling the West Point curriculum, which had drifted toward a great emphasis on engineering and the physical sciences. ''The cadets should not live in a mental cloister,'' he said. ''Their interests must be catholic, avoiding the small horizons sometimes attributed to military men.''

The new superintendent also de-emphasized football at West Point, a national powerhouse at the time. The game against Notre Dame, once an annual event, was dropped after the 1947 contest and not resumed until 1957. Chief of Berlin Government

In January 1949, General Taylor became Chief of Staff of American Forces in Europe. That September, he was appointed the first commander of the American Military Government in Berlin, which the Allies had divided into American, British, French, and Soviet sectors.

His conduct as leader of the 3,000-man Berlin garrison in a constantly ticklish situation - there was much friction between the Soviet commander and the Allied commanders - won General Taylor a high-level post in the Pentagon, where he served from 1951 to 1953 as Deputy Chief of Staff for Operations and Administration.

General Taylor, who succeeded Gen. James A. Van Fleet as commander of the Eighth Army and United Nations forces in Seoul early in 1953, planned strategy for some bitter fighting in the closing months of the Korean War. He did so while hewing to instructions from President Eisenhower, who was trying to arrange an armistice, not to rout the enemy but to contain him. After an armistice was signed July 17, 1953, the general remained in Seoul to arrange prisoner exchanges, reinforce South Korea's army, and direct the Eighth Army's efforts to help rebuild the war-torn country.

When General Taylor became Army Chief of Staff in June 1955, he succeeded General Ridgway, who had alienated President Eisenhower by pushing for a large army. It was a time of change and the President, despite his own Army background, had sided with the Air Force view favoring, as the country's first line of defense, development of a massive nuclear strike-and- retaliation potential. Conflict on Military Policy

General Taylor came into almost immediate conflict with the chairman of the Joint Chiefs of Staff, Adm. Arthur W. Radford, who had President Eisenhower's staunch backing and favored the massive nuclear strike-and-retaliation line. It was General Taylor's view, which he expressed with increasing frustration, that the nation's military policy should be based on ''flexible response.''

''Air power is our initial line of defense,'' he conceded, ''but no one has proved to my satisfaction that we will have only world wars to be settled only by big bangs. Specific cases have a way of differing from expected patterns, in many ways, but infantrymen at one time or another become indispensable. Nothing we have discovered or expect to discover will reduce the need for brave men to fight our battles. The atom bomb is no weapon to counter a coup d'etat. Airborne troops appear to be an ideal force to police the free world.''

But at meetings of the Joint Chiefs of Staff, General Taylor's ideas usually fell on deaf ears. He later recalled he had been outvoted on 20 of 23 major issues by Admiral Radford and the Air Force Chief of Staff. And so, in 1959, he resigned as Army Chief of Staff and requested retirement.

''For four years I have struggled to modernize the Army, and my success was limited,'' he said, adding with heavy sarcasm: ''So I decided I would do one thing for the country and withdraw an obsolescent general from inventory.'' Book Presents Position

General Taylor's service to his country was far from over, however.

He wrote ''The Uncertain Trumpet,'' its title taken from I Corinthians 14:8: ''For if the trumpet give an uncertain sound, who shall prepare himself for battle?'' The book severely criticized the Pentagon's organization, reviewed General Taylor's controversies with the Joint Chiefs of Staff under President Eisenhower and advocated scrapping the Joint Chiefs of Staff. General Taylor recommended substituting a single Chief of Staff with control of an integrated military budget.

General Taylor served briefly as board chairman of an electric company serving Mexican communities and as president of the Lincoln Center for the Performing Arts in New York City.

Following the Bay of Pigs catastrophe in 1961, President Kennedy, who had publicly assumed full responsibility for the debacle, yet felt he had been ill-served by the Central Intelligence Agency and the Joint Chiefs of Staff, called on General Taylor to conduct an investigation of the affair. The general concluded that, in the future, the C.I.A. might be allowed to continue small-scale undercover activities but should not be permitted to take an operational role in major undertakings of the magnitude of the Cuban invasion. Drafted by Kennedy

President Kennedy, who had become disenchanted with the advice he was getting from the Joint Chiefs, created the new White House post of Military Representative of the President and persuaded General Taylor to return to active duty and accept it in July 1961. The President also made General Taylor his personal watchdog over the nation's intelligence apparatus.

Mr. Kennedy depended on the general for advice on the crisis over Berlin, which led to construction of the wall that separated East Berlin from West Berlin, and other military-political problems, notably the gathering storm in Vietnam.

Considering General Taylor's past difficulties with the Joint Chiefs of Staffs, his appointment by President Kennedy, in September 1962, to be chairman of that body was not without irony. The general made no rush to make over the defense establishment in his own image, however, apparently because of the escalating Vietnam War. He did note, however, that the nature of that conflict, the Cuban crisis, and other ''small wars'' lent strength to his argument that highly mobile forces capable of distant strikes had only begun to demonstrate their usefulness. Ambassador to Saigon

General Taylor continued as chairman of the Joint Chiefs after President Kennedy was assassinated on Nov. 22, 1963, and succeeded by Lyndon B. Johnson. Two years later, as Vietnam was receiving more and more military support from the United States, President Johnson asked the general to become Ambassador to Saigon. He resigned that post in 1965, but continued to serve as a special consultant to Mr. Johnson until 1969.

In 1984, General Taylor listed what he called three major lessons the United States should have learned from the Vietnam War.

''The first is that before we ally ourselves to another country, we must ascertain to what extent they can exploit our help,'' he said. ''We know the great effort we expended on Vietnam. The large percentage of the effort was unusable.

''Second, we should declare war. President Johnson thought the Tonkin Gulf Resolution ample, but it was not. Many of the opponents of the war were noisy and felt that they were being patriotic by complaining about the policies of President Johnson. In case of war, we would have said they had to rally around the flag, which they did not do.''

The third lesson of Vietnam, General Taylor said, was ''you should never let television on the battlefield.'' He added: ''In World War II, the press was admirable because they felt they were American citizens and that their country was sacred. In Vietnam there was the feeling on the part of some of the press that their task was to destroy the American command and to work against what was being done. That kind of thing should not be tolerated.''

In retirement, General Taylor occasionally testified before Congressional committees concerned with military matters, and continued to write articles for military and foreign affairs publications. Among his books were ''Responsibility and Response'' (1967) and ''Precarious Security'' (1976).

General Taylor maintained a home on Washington's Embassy Row with his wife, the former Lydia Gardner Happer, whom he married in 1925 and who survives him. Also surviving are their two sons, John Maxwell, who went to Williams College, and Thomas Happer Taylor, who was a West Point graduate and Army officer.

Of his son Thomas, General Taylor once remarked: ''He did something at the Academy that I could never do. He made the choir.''

The Army spokesman, Major Bell, said the funeral will be at 10 A.M. Thursday at the Memorial Chapel of Fort Myer, Va., to be followed immediately by burial at Arlington National Cemetery.