Herbert Threlkeld Edwards Jr., 76, a retired official of the U.S. Information Agency, died in New York City Tuesday after a heart attack.

He was stricken while on tour with his wife, India Edwards, former vice chairman of the Democratic National Committee, to promote her new book, "Pulling No Punches, Memoirs of a Woman in Politics."

Former residents of Washington for many years, they had returned here last week in connection with the book. They moved to California in 1971, and had lived in Greenbrae near San Francisco since early 1976.

Born in Bethlehem, Pa., Mr. Edwards was a graduate of the University of Pennsylvania. He spent a number of years as a volunteer assistant to Sir Wilfred T. Grenfell, head of the International Grenfell Association, doing medical and social work in Labrador and Newfoundland.

During that period, Mr. Edwards became interested in documentary movie pictures and became a professional in that field.

In 1942, he joined the newly created division of cultural affairs of the Department of State. When the U.S. Information Agency was established after World War II, he was named assistant administrator and director of its international motion picture program.

The program produced and distributed documentary films, newsreels and animated films that were recorded in more than 50 languages.

He left USIA in 1953 to make surveys for various organizations, including the United Nations. One survey concerned a sampling of American citizens in an effort to determine how they felt about the U.N.

Mr. Edwards returned to the USIA in about 1960. He retired in 1970.

In addition to his wife, he is survived by a sister, Rhoda Thorpe, of Bethlehem; a stepdaughter, Mrs. John Williams, of Belvedere, Calif., and five grandchildren.

A memorial service will be held at 2 p.m. Saturday at St. Alban's Episcopal Church here.

The family suggests that expressions of sympathy may be in the form of contributions to the Girls Clubs of America, 133 E. 62d St., New York City.