A civilian instructor at an Air Force intelligence school in Texas has been reinstated despite his refusal to sign a controversial secrecy pledge, the service said yesterday.

The Air Force, in a prepared statement, said Louis C. Brase was informed yesterday that his access to "sensitive compartmented information" had been restored and that he was free to resume work as a "cryptological maintenance training manager" at Goodfellow Air Force Base in San Angelo, Tex.

The decision came a day after Brase and two other Pentagon workers joined the American Federation of Government Employees in filing a lawsuit in U.S. District Court, challenging the constitutionality of Standard Form 189.

The Air Force said Brase's involvement in the suit had no bearing on its decision. Rather, it said the decision was prompted by the Reagan administration's decision to temporarily halt enforcement actions, pending resolution of an earlier suit filed by the National Federation of Federal Employees.

The form asks workers to acknowledge the government's right to fire or prosecute them on criminal charges for releasing classified or "classifiable" information.

But critics say the form is so broadly worded that employes are being asked to sign away their rights.

Brase was temporarily moved to another job on Aug. 4 after questioning a demand by his superiors that he sign the form.