Don Freeman, 80, a well-known artist and author of children's books, died Wednesday in New York City after a heart attack.

A resident of Santa Barbara, Calif., he was stricken while on a business trip. He had planned to attend the opening of an exhibition of his work next week in Greenwich Village.

Mr. Freeman had won many awards for his children's books. They included "Pet of the Met," the story of Maestro Petrini, a mouse who lived in the Metropolitan Opera House and had to cope with his chief enemy, Mephisto the cat.

His other picture books included "The Circus in Peter's Closet," "Mop Top" and "Norman the Doorman," about another mouse who lived in knight's castle.

After giving a chalk talk at a Washington Post Children's Book Fair, Mr. Freeman said, "I like the free kind of loose drawing full of easy imagination. I like things to be kind of theatrical - it's a weakness I have . . .

"I think a child has a lot of imagination and pictures for children should be free and easy and not forced. I'd love to arrive at the point where you can tell a story with just pictures - it can be done.

"I just think a book - well it's almost a theater . . . When you open a book, it's like the curtain rising and you're transported away."

When he was not writing and illustrating books (with his wife Lydia), Mr. Freeman was sketching New York life and Broadway scenes. His sketches appeared frequently in The New York Tims and the old New York Herald Tribune.

In addition to writing many other books, he also had done illustrations for William Saroyan's "The Human Comedy" and "My Name Is Aram" and "The White Deer," written by James Thurber after the noted cartoonist had become blind.

Born in San Diego, Calif., Mr. Freeman attended the School of Fine Arts there. He first went to New York to study at the Art Students League, and played trumpet in jazz groups at night.

He decided to concentrate on art after he accidentally left his trumpet on a subway train one night, he once explained.

In addition to his wife, he is survived by a son, Roy. of Zurich, Switzerland.