John Hughes, director of the Voice of America for the past four months, was named yesterday to be the new chief spokesman for the State Department.

The choice fills an important vacancy for Secretary of State George P. Shultz, but leaves another at the VOA, which has run through four directors in the past two years.

Hughes, 52, will replace Dean Fischer, former Washington news editor for Time magazine, who said he would step down after Alexander M. Haig Jr. announced his resignation as secretary.

Until last week, Hughes and Shultz were strangers. However, the VOA chief is no stranger to the reporting of foreign affairs.

A longtime staffer for the Christian Science Monitor, Hughes won a Pulitzer prize for international reporting in 1967 for "thorough reporting of the attempted communist coup in Indonesia in 1965 and the purge that followed . . . ." While working for the Monitor, Hughes reported from Africa and the Far East and also served as a correspondent for Westinghouse Broadcasting Co.

He went on to serve as managing editor and editor of the Monitor, then president, publisher and editor of Hughes Newspapers Inc. of Orleans, Mass. He is a former president of the American Society of Newspaper Editors and a former Nieman fellow at Harvard University.

Hughes said Shultz offered him the job after the two men met for 45 minutes last Thursday. Hughes slept on the offer, then accepted it the next day.

Hughes said that, on the basis of his conversations, he believes that Shultz is dedicated to a free flow of information between the State Departemnt and the press. "I hope to be a useful bridge," he added.

During the Haig-Fischer era at State, correspondents complained that information coming out of the department had dropped to an all-time low in substance.

Hughes is a native of Wales, who became a U.S. citizen in 1965.

Before taking over as head of the VOA, he had served as associate director for programs of the International Communication Agency, the VOA's parent agency. He took over the Voice after President Reagan's first appointee, James B. Conkling, resigned amid attacks from left and right. The agency has been buffeted by those who think it should be a propaganda arm and those who want more journalistic independence.