The Kennedy Center and the Library of Congress are combining resources to set up a library of the performing arts with a computer link between the two institutions.

An actor, producer or musical director using the library will be able to compare earlier productions, translations and role interpretations by apping the vast collections at the Library of Congress.

For the public, the library will be a source of permanent exhibitions and rotating shows keyed to musical and theatrical productions running at the Kennedy Center.

Plans for the library for the performing arts - expected to be in operation within six months - were announced yesterday by Daniel J. Boorstin, the Librarian of Congress, and Roger L. Stevens, chairman of the Kennedy Center.

They told of their plans surrounded by samples of memorabilia from the Library of Congress collections - an 1898 Edison recording machine with wax cylinders, a poster for an old Othello production, the original manuscript of an Aaron Copland composition and drawing of a ballet costume for a French company.

Boorstin said the Library hopes to make oral history recordings with performers and playwrights. Another posibility is the videotaping of dance, theater and musical productions for the record.

Union rules governing taping of live performances are strict and complicated. But Martin Feinstein, the center's executive director, said that he hopes negotiations can be made out to tape for historical record only with prohibitions on copying or public performances.

A core reference collection of 3,000 to 5,000 volumes will be housed in the new library facility on the Kennedy Center's top floor at the end of the North Gallery. That will place it near the new studio theater and the new musical theater lab in the multi-purpose room.

Architect Philip Johnson is designing the two-story library center.

As to the cost, Stevens said he had a figure "in his head." "Not much money was involved," he emphasized, but refused to give a figure. He said the money came from the Kennedy Center's private funds and wouldn't be that much since the walls, plumbing, heating and basic housing are already.

In its first stage, the Center's reference facility will be linked by computer to the Library of Congress. A theatrical professional or a researcher will be able to get a bibliographioc list of material avaible by making a query through the computer. Then the books, manuscripts and other library materials can be delivered to the Kennedy Center.

Later, will closed-circuit televisions, a poster could be pulled from the Library's collections and transmitted downtown to the Center, said Alan Fern, director of research at the Library.

Boorstin envisioned future computer link-ups with other holding of performing art libraries. Among these are the Luncoln Center Library. Museum of Performing Arts, which houses of the New York Public Library collections.