Construction is scheduled to begin in 18 months on what planners said will be one of the largest academic research libraries in the country, a $21 million center in Prince George's County that will link by computer eight of the area's university libraries and provide central storage for the schools' rare books.

More than 160,000 students and 3,800 faculty members will have computerized access to the electronic card catalogue that will list 16 million books, magazines, maps and other library holdings.

Officials of the newly formed Washington Library Consortium unveiled plans for the facility yesterday. George Washington and George Mason universities will be the first to catalogue their total library holdings electronically.

"We think it is a major contribution to academic and intellectual life in this area," said the Rev. John P. Whalen, executive director of Washington's Consortium of Universities. "We have the ability to create a world-class academic library to be available to all participants without any library giving anything away."

The schools that make up the Washington Library Consortium are American, Georgetown, George Washington, Catholic, George Mason, Gallaudet and Marymount universities and the University of the District of Columbia.

Money for the "superlibrary" project will come from several sources, including an expected $7 million appropriation from the U.S. Department of Education's higher education academic facilities fund. Whalen said that a fund-raising effort that started yesterday, and, if necessary, a tax-exempt bond issue by Prince George's County would supply the rest. The universities will shoulder the annual operating cost, expected to be $1.3 million in the first year of operation.

The linkup would be the first venture of its kind in the country, advocates said. National library experts said there are other library groups that share an automated system, such as the one at the University of Illinois, and a few that have a central storage facility, such as the University of California system.

But the Washington area venture is considered unique because it will have both a computerized card catalogue and a central repository for little-used books. There also will be a combined collection development program and a program to preserve old and rare books.

"If they actually can bring off creating integration of the catalogues and documents in all those libraries so that the ease of access of information is equalized across geographic locations, that is an exciting development," said Shirley Echelman, executive director of the Washington-based Association of Research Libraries.

The storage facility, at Rte. 301 in the Prince George's County-owned Collington development near Bowie, eventually is to house about 2 million obscure or rarely used books. Construction on the first 40,000-square-foot building is to start in 18 months and be completed a year later. The Prince George's facility will house the central computer equipment and will have areas for researchers to study.

An additional 7 million books and 9 million other library holdings will remain at the eight campus libraries but will be a part of the system. The largest academic research library is at Harvard University, with 11.1 million volumes, followed by Yale University with 8.3 million.

Under the plan, students and faculty at the participating universities will be able to use 1,200 computer terminals placed in campus libraries, academic offices and dormitories to request delivery of a book within 24 hours.

The director of libraries at the College Park campus of the University of Maryland, which was approached by the consortium to join in the effort, said the school has a "wait and see" position on the project.

"Our first responsibility is to serve our own people," said Joanne Harrar, who said the university shares library resources among its campuses. "It isn't clear to us that what has been proposed will come to pass. If it does we would like to evaluate it and join at that time."