Kenneth MacLeish, 60, a senior assistant editor of National Geographic and a former senior editor of Life magazine, died of cancer Friday at his home in Annapolis. "He was a truly gifted writer who was highly admired by all Geographic writers for his Sensitive style and mastery of the writing craft," said Gilbert M. Grosvenor, editor of National Geographic.

Although he was stricken with cancer five years ago, Mr. MacLeish continued to write and his last published article, on Leonardo da Vinci, will appear in the magazine's September issue. His story on Mont-Saint-Michel appeared in June.

Mr. MacLeish was a skilled diver and at one time shared the record for the deepest underwater dive - 724 feet. For a National Georgraphic story in 1967, he made a descent in an experimental research submarine and stepped out onto the ocean floor at 420 feet. It was the deepest exit that had ever been made from a submarine.

Mr. MacLeish, whose father was poet Archibald MacLeish, was born in Cambridge, Mass., and received bachelor's and master's degrees from Harvard.

During World War II he served as a Navy officer and piloted a blimp over the Atlantic on antisubmarine patrols.

He joined Life magazine after the war and served as science editor, directed special projects and produced a number of books before being promoted to senior editor and reporting on Europe and North Africa.

He joined the National Graphic in 1963, and was made a senior assistant editor in 1968. In addition to winning a reputation as a sensitive and prolific writer of articles, he helped direct the magazine's foreign staff.

He formerly was married to Carolyn de Chadenedes MacLeish, who lives in Annapolis. Survivors include his parents, who live in Conway, Mass., and four children. Martha Fuller, of Somerville, Mass., Ellen Zale, of Baltimore, Bruce A., of Bowling Green, Ky., and Kennetth I. of Amherst, Mass., a brother, William, of Falmouth, Mass., a sister, Mimi Grimm, of Kensington, and two grandchildren.