Dr. John J. Dillion, 62, a former president of Mount St. Mary's College in Emmitsburg. Md., died of cancer Friday in a hospital in Gettysburg. Pa.

Dr. Dillon was the 20th president of Mount St. Mary's, which was founded in 1808 and is the oldest independent Catholic college in the United States. He also was the first layman to head the institution. He was president from 1971 to 1977, when he resigned the position to resume his career as an English professor at the college.

Mount St. Mary's was an all-male school with an enrollment of about 800 when Dr. Dillon became president. It became a coeducational institution with an enrollment of about 1,300 students during Dr. Dillon's tenure.

He began his career with the college in 1940 shortly after earning a doctorate in English at the University of Pittsburgh in Pittsburgh, where he was born. He was chairman of the English department from 1940 to 1968, director of public relations from 1951 to 1959, director of athletics from 1951 to 1968, and executive vice president from 1968 to 1971.

Dr. Dillon was a member of the Association of Independent Colleges of Maryland, of the American Council on Education, of the Association of American Colleges, and of the National Council of Teachers of English. He also was a member of the board of trustees of Villa Julie College in Stevenson, Md., a member of the Knights of Columbus, of chairman of the advisory committee for the Victor Cullen Center for the Mentally Retarded in Sabillasville, Md.

Dr. Dillon's survivors include his wife, the former Ruth McDonald, of the home in Blue Ridge Summit, Pa.; a son, John J. Dillon III, of Newark, Del,; two brothers, Thomas P. Dillon, of McLean, Va., and Bill Dillon, of Rochester, N.Y., and one granddaughter.

The family suggests that expressions of sympathy be in the form of contributions to the John J. Dillon Memorial Fund, c/o Mount St. Mary's college, Emmitsburg, Md. 21727.