Hollywood, Feb. 1--Buster Keaton, the poker-faced comic whose studies in exquisite frustration amused two generations of movie audiences, died of lung cancer today at his home in suburban Woodland Hills. His age was 70.

Someone once remarked of Buster Keaton that he looked like the kind of man that dogs kick.

A mournful little fellow sad-faced as a basset, usually wearing a saucer-brimmed porkpie hat, oversized suit and floppy bow tie, Joseph Francis Keaton stood with Charlie Chaplin and Harold Lloyd as one of the three great clowns of the silent screen.

In 30 or more films, mostly two-reelers, filled with pratfalls and custard pie slapstick, Buster Keaton established an unforgettable character--the sad and silent loner who persevered stoically against a mechanized world.

Unlike Mr. Chaplin, he was never sentimental and he never resorted to maudlin pathos. He turned a granite face to the wildly comic and nightmarish cries that befell him--and he always prevailed over impending doom.

His strength was his ability to survive. He displayed that perseverance not only in his comic characterizations but also in his private activities.

For his life was marked by periods of triumph and frustration--wealth, a descent into poverty and alcoholism, and then, in his twilight years, a return to riches, recognition and contentment.

His period of greatest productivity was in the early and mid-1920's. In those light-tax days, Buster's salary soared to $3,500 a week, and he built a $300,000 house in Beverly Hills.

A great pantomimist, the equal of Mr. Chaplin in comic inventiveness, he was held even superior to "the little tramp" in acrobatic grace. Mr. Keaton never used a double. His ability to take a violent fall without breaking a bone was the marvel of the day.

Most of Mr. Keaton's films were made without a script.

"Two or three writers and I would start with an idea and then we'd work out a strong finish and let the middle take care of itself, as it always does," Mr. Keaton recalled in an interview two years ago.

"Sometimes, we'd work out a gag in advance; other times, it would work itself out as we went along. In those days we didn't use miniatures or process shots. The way a thing looked on the screen was the way you'd done it."

When the movies began talking, Buster Keaton dropped out of sight. The public wanted voices, and Buster's pantomime technique failed to hold up.

Hard times and marital troubles piled up. After 11 years of marriage (and two sons), he and Natalie Talmadge, sister of the beautiful actresses Norma and Constance, were divorced in 1932. His second marriage, to Mae Scribbens, ended in divorce in 1935.

In 1934, filing for bankruptcy, Buster listed assets of $12,000 and liabilities of $303,832.

Mr. Keaton was down but never quite out. Just when life seemed as hostile as a paranoid's nightmare, things began to look up. His third marriage, to Eleanor Norris, a 21-year-old dancer, in 1940, brought stability. She survives him, as do his two sons.

Video Star in Britain

British television rescued him from obscurity in the early 1950's. It brought him fresh fame, a comfortable income and a new public. He appeared on most major television shows in London and was paid from $1,000 to $2,500 for each performance.

In 1956 Paramount paid him $50,000 for the rights to "The Keaton Story," a film tracing Mr. Keaton's rise from vaudeville to Hollywood stardom, with Donald O'Connor playing the title role.

Mr. Keaton used the money to buy a ranch-type house and an acre and a half of farmland in the San Fernando Valley. He kept busy, making several filmed television shows in Hollywood and appearing in several acting engagements.

Reissued "The General"

But it was his old silent movies that brought in the gold. Mr. Keaton had had his own producing company in the 1920's and he retained ownership of his old films. He had the film quality restored and a sound track of music added. The pantomime remained intact and the old subtitles were kept.

The first reissue was of "The General"--a slapstick classic of a bumbling Civil War spy-- in 1962. It played all over Europe. People laughed harder than they did in 1927, when the film first came out.

Mr. Keaton wrote the story and continuity of "The General," directed it, cut it and played the leading role. It was shot in 18 weeks at a cost of $330,000. It contained one of the great chases in movie history: Mr. Keaton's attempt to tame a runaway train during the Civil War.

Mr. Keaton's renaissance reached an artistic peak last October at the Venice Film Festival, when "Film," an arty 22-minute silent he made in New York in 1964, was accorded a five-minute standing ovation. Fighting back tears, Mr. Keaton told a correspondent: "This is the first time I've been invited to a film festival, but I hope it won't be the last."

Critics differed on "Film," Samuel Beckett's first screenplay, a story of an old, obsessed man who shuts himself up in a room to thwart fate.

But there was no dissension over the wonderfully comic image Mr. Keaton gave the world in his old two-reelers such as: "The Cameraman," "Steamboat Bill Jr.," "The Passionate Plumber," "Sherlock Jr." and in a full-length classic, "The Navigator."

"The Navigator" contained the unforgettable scene of Mr. Keaton trying to shuffle stuck- together cards. And then there was the memorable sequence when he launches a ship: he stood at attention on deck, resplendent in admiral's uniform, riding it down the ways, never blinking or wavering as it sank slowly out of sight.

Early in his career Buster Keaton learned that a stoic countenance drew laughs.

He was born to the stage. His parents, Joseph and Myron Keaton, were appearing in a tent show with Harry Houdini, the magician, when the future comedian arrived on October 4, 1895, while the show was playing Piqua, Kan. It was Houdini who coined the nickname.

"What a buster!" Houdini is supposed to have exclaimed when the six-month-old baby fell downstairs.

That was only the first of countless pratfalls. In the family act, which became one of the roughest knockabout low-comedy turns in vaudeville, Buster was tossed around by Pop with murderous abandon while Mom, oblivious to the chaos, essayed a saxophone solo downstage.

It was around that time that Buster perfected his stoic mask while still a child performer. Hit on the face with a broom, he would wait five or six seconds without moving a facial muscle, and then say "Ouch." It always brought down the house.

The Keatons did their last variety turn at the Palace in 1917. They were signed by the Schuberts for "The Passing Show of 1917" but Buster was sidetracked by Roscoe (Fatty) Arbuckle, who talked young Keaton into taking a supporting role in a two-reeler called "The Butcher Boy." In this opus Buster was dumped in molasses, bitten by a dog and hit with an apple pie.

Soon Buster became an expert on the composition of slapstick pies. "First, you had to make it with a double crust on the bottom, so you could get a good hold on it without your fingers going through," he once recalled. "Then you made the filling of the pie out of flour and water uncooked, so it would be sticky and stringy, and you topped it off with, say, blueberries and whipped cream, or perhaps a nice meringue. I never threw a pie in any of my feature-length pictures. By then we thought pies were pretty silly."

In recent years Buster took great satisfaction in the knowledge that a new generation was finding his old films funnier than ever. And although he still refused to smile when a camera was on him, he had to concede that life hadn't been too bad. He was making better than $100,000 a year from commercials alone.

"I can't feel sorry for myself," he said in Venice last fall. "It all goes to show that if you stay on the merry-go-round long enough you'll get another chance at the brass ring. Luckily, I stayed on."