William M. DuChessi, 64, executive vice-president of the Amalgamated Clothing and Textile Workers Union, AFL-CIO, died of cancer Saturday at the National Institutes of Health.

He also was assistant director of the union's textile division.

Mr. DuChessi came to Washington in 1967. He served as director of the Committee on Political Education (COPE) and legislative department of the Textile Workers Union of America, a predecessor of the Amalgamated Clothing and Textile Workers Union.

He was elected general secretary-treasurer of the TWUA in 1972, then, following its 1976 merger with the Amalgamated Clothing Workers of America, became executive vice-president and legislative director of the new union, posts he held until his death.

Mr. DuChessi had been treasurer of the Inter-American Federation of Textile and Garment Workers, a member of the executive board of the League for Industrial Democracy, the general board ot the AFL-CIO Industrial Union Department, and a member of the AFL-CIO National COPE Operating Committee.

He was named to the Commission on Administrative Review of the House of Representative by then Speaker Carl Albert (D-Okla.).

Mr. DuChessi was a native of Amsterdam, N.Y. He went to work in a local carpet firm at the age of 14, becoming a member of the TWUA in 1937. He later joined the union's organizing staff and worked in upstate New York until 1944.

Following World War II Navy service in the Pacific, he returned to the union, first as county joint board manager in New York, then as regional director for Maryland and West Virginia.

Mr.DuChessi was elected vice-president and member of the TWUA Executive Council in 1955.

Survivors include his wife, Shirley, of the home in Chevy Chase; a son, Air Force T/Sgt. Mariano, of Dover, Del.; Three brothers, three sister, and two grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to the American Cancer Society. CAPTION: Picture, WILLIAM M. DUCHESSI