The former president of a California-based explosives firm pleaded guilty in U.S. District Court here yesterday to a conspiracy charge in connection with the alleged shipment of munitions and weapons to a terrorist training school in Libya for use there in a school for terrorists.

Jerome S. Brower, 61, who was president of J.S. Brower and Associates of Pomona, Calif., faces up to five years in jail, and a $10,000 fine or both on the charge of conspiracy to violate various federal arms transportation laws. He will be sentenced later. Judge John H. Pratt, who accepted Brower's guilty plea yesterday, has not yet scheduled sentencing.

Brower and two other men, Frank E. Terpil, 40, of McLean and Edwin P. Wilson, 51, of Upperville, Va., both former CIA employes, were indicted last April in connection with operation of the terrorist training school. Both Terpil and Wilson are fugitives and are believed to be out of the country.

Asst. U.S. Attorney E. Lawrence Barcella Jr. told Pratt yesterday that the government's evidence would show that Brower's role was to help Terpil and Wilson allegedly fulfill a contract they had with the Libyan government in 1976 to supply explosive devices.