Jean Stafford, 63, who won the Pultizer Prize for fiction in 1970 for a collection of her short stories, died of cardiac arrest Monday at the Burke Rehabilitation Center in White Plains, N.Y. She had ill in recent years with a bronchial ailment.

In addition to her short stores, which first appeared in The New Yorker, Harper's Bazaar, Vogue and other magazines, Miss Stafford wrote novels that received high critical acclaim and one lengthy piece of reportage, "A Mother in History," which was based on interviews with Marguerite Oswald.

A recurring theme in her work was the idea that people are imprisoned, in effect, by their own personalities, their surroundings and relationships with others and by the interaction between the two. She herself was a westerner by birth and upbringing and an easterner by choice. But her sense of place remained strong and it was an integral part of her writing.

"As soon as I could, I hotfooted it across the Rocky Mountains and across the Atlantic Ocean," she wrote in the preface to "Collected Stories," which was published in 1969. "But my roots remain in the semi-fictitious town of Adams, Colo. I have borrowed titles from Mark Twain and Henry James, who are two of my favorite American writers and to whose sense of place I feel allied."

"place" and "dislocation" were important parts of her first novel, "Boston Adventure" (1944) which established her reputation. it was the story of an outsider trying to make her way in the closed upper reaches of New England society.

Her secon novel was "The Mountain Lion" (1947), an allegorical study of adolescence set in the mountains of Colorado. The New Yorker hailed it for its "subtlety and understanding." "The Catherine Wheel" appeared in 1952. A reviewer in Commonwealth described it as "a novel to compel the imagination and nurture the mind. . .(and) one which pity and terror combine to reach us in the secret, irrational places of the heart."

But Miss Stafford may best be remembered for her short stories. Thirty of them were included in her "Collected Stories." They were grouped under four subtitles: "The Innocents Abroad," "The Bostonians and Other Manifestations of the American Scene," "Cowboys and Indians and Magic Mountains" and "Manhattan Island."

Thomas Lask, a reviewer for The New York Times, wrote of the book: "Everything that we desire from a collection of short stories, from the art of fiction, if fact, can be found in this gathering of jean Stafford's work: a superior and controlled craftsmanship, human dilemmas uniquely individual, yet common to all of us, backgrounds and situations authentic in themselves and perfect for providing the skeletal structure of her tales, and those insights into human behavior and personality that we call wisdom."

Miss Stafford's style and sense of literary economy struck Pete Axthelm, a Newsweek reviewer, this way:

"Jeans Stafford can teach almost anything one could want to know about swifty and deftly developing characters balancing them in delicated counterpoint or wrenching conflict, and probing their thoughts and emotions."

He added, however, that while many of the stories, "taken individually . . .show how much can be accomplished in a few pages, taken together, they unfortunately dramatize some of the limitations of Miss Stafford's genre."

For her writing remained strongly in the tradition of the Henry James and Mark Twain. Robert Giroux, the publisher of all of her books, visited her the day beford her death. The two books on her bedside table, he said, wer "Roughing It," by Twain, and a collection of Flannery O'Connor's letters.

Jeans Stafford was born in Covina, Calif. She grew up in Boulder, Colo. (Some critics though that the fictional Adams, Colo., was Boulder.) Her father, John Richard Stafford, wrote western stories under the name of Jack Wonder. He also wrote a book under his own name, called "When Cattle Kingdom Fell."

Miss Stafford described that book as one of the important ones of her childhood. Another, she said, was called "Stepdaughter of the Prairie," by Margaret Lynn, a cousin of Miss Stafford's mother.It was a memoir of Miss Lynn's girlhood on the Kansas frontier.

Miss stafford graduated from the University of Colorado and then spent a year at the University of Heidel-berg, Germay. Back in the United States, she taught for a year at Stephens College in Columbia, Mo., and then spent a year in Tennessee working on The Southern Review.

She eventually moved to Boston, where she married the poet Robert Lowell, the first of her three husbands. He dedicated his first book, "Lord Weary's Castle," to her. It won him the Pulitzer Prize.

Her marriage to Lowell ended in divorce. Her second marriage, to Oliver Jensen, also ended in divorce. In 1959, she married A. J. Leibling, the late columnist and press critic of The New Yorker. They lived in East Hampton, Long Island, and Miss Stafford continued to live there until her death.

For all the tragedy of which she wrote, Miss Stafford was a woman of both privacy and wit.

Giroux, her publisher, recalls taking her to see the film version of "Romeo and Juliet." He said many youngsters were at the performance and that he and Miss Stafford walked out of the theater behind a group of them who were exclaiming about the romance and glamour of it all. According to Giroux, Miss Stafford suddenly leaned forward and said to the group, "And wasn't it well written?

Miss Stafford's survivors include two sisters, Mary Lee Frichtel, of Hayden, Colo., and Marjorie, who lives in Oregon.