Retired Maj. Gen. Moody R. Tidwell Jr., a former assistant judge advocate general of the Air Force, died Saturday at his home in Washington. He had a heart ailment.

Gen. Tidwell earned his law degree from the University of Oklahoma in 1923 and was commissioned a second lieutenant in the Army reserves in the same year. He was a banker in Miami, Okla., his home town, from 1923 to 1928 and then practiced law until 1940.

He was called to active duty in the Army in that year and was assigned to Washington, where he was chief of the claims division in the office of the chief of finance in the War Department. He later served on the War Department board of contract appeals.

Gen. Tidwell opted for the Air Force when the Army Air Corps became a separate service. From 1949 to 1952, he was stationed in Japan, where he was staff judge advocate general for the Air Force's Far East Command.

From 1952 to 1960, he was staff judge advocate for the Air Materiel Command at Wright Patterson Air Force Base in Dayton, Ohio. He was named assistant judge advocate general of the Air Force in Washington in 1960 and held that post until his retirement in 1963.

Gen. Tidwell's military decorations include the Legion of Merit with two oak leaf clusters.

His survivors include his wife, Dorothy, of the home; a son, Moody R. III, of Fairfax; two brothers, Robert, of Seattle, and William, of Houston; a sister, Marguerite Gregory, of Carmel, Calif., and two grandsons.

The family suggests that expressions of sympathy be in the form of contributions to the Air Force Aid Society, 1117 North 19th St., Arlington, Va., 22209.