Plans for a multimillion-dollar Dulles World Trade Center with a 372-room hotel and acres of permanent exhibit space were revealed recently by Washington builder-developer Michael G. Cappy.

The developer said that he has acquired a 60-acre site at the southeast intersection of the Dulles airport road and Rte. 657, two miles east of the airport. He said the first phase, to start this spring, will include a 145,000-square-foot trade center and exhibition hall and a "full-scale luxury hotel."

Cappy said the first phase should be completed in 1980 and one million square feet of office and exhibit area will be ready in five years.

Architectural plans for the $23 million first phase of construction have been prepared by Charles W. Englehart of Annapolis. Cappy said the trade center would enable both American and foreign manufacturers to display their products and have offices under one roof near an international airport.

"There are similar flourishing trade centers in major foreign cities and in New York, Boston, Dallas, Houston, San Francisco and Los Angeles," added Cappy. "I am convinced that we can attract manufacturers of products from cameras to hardware items."

David Edwards, executive drector of the Fairfax County Economic Development Authority, commented that the project sounds promising and that the entire Dulles area appears primed for more international trade-related development. He cited Virginia plans for construction of toll lanes for access traffic along the present Dulles non-access highway as contributing to recently increased interest in new development from Reston to the airport.

Land transactions and prices have been increasing in the Dulles area in recent months, according to broker William Bryant.