A pair of shopping centers in Laurel will be linked together to create a 150-store mall halfway between Washington and Baltimore, developers and local officials announced yesterday.

The Shopco Company, a New York developer that runs 150 shopping centers, said it will begin work on the project as soon as negotiations with contractors can be completed.

The new center will open in the spring of 1979, said William Bulla, the firm's director of management and operations.

The site, on the west side of Route 1, has been designated by Laurel and Prince George's County officials as a major shopping complex for 15 years.

The project will connect the present Laurel Shopping Center with a Montgomery Ward store about a block away. A new, two-level, 265,000-square-foot mall with room for 90 stores and a 140,000-square-foot J.C. Penney store will be built between the present buildings.

An enclosed, elevated walkway will connect the Penney store to the present Laurel center, where the major merchants are The Hecht Co., Giant Food and Peoples Drug.

The new construction will cost $30 million, including a two-level parking structure, Bulla said.

With the present 424,000-square-foot shopping center, about 160,000 square feet in the Ward's store and more than 400,000 square feet of new buildings, the project adds up to nearly a million square feet of retail space.

$10 million second phase calls for construction of a another department store and a second parking structure.

Bulla said the center is expected to do $100 million worth of business its first year and to grow to a $160 million a year operation by 1985.

As part of the Shopco/RIDC Group the developer manages about 15 million square feet of retail selling space and was ranked as the ninth largest shopping center developer last year by Mall Monitor, a trade publication.

Innovations in the Laurel Center include a "food boutique" similar to the restaurant complex at White Flint Mall called The Eatery, and a boutique carousel of eight small shops that will revolve once every 40 minutes.