Chief Justice Warren E. Burger cleared the way last night for the federal government to institute a series of controversial changes in regulations governing pay raises, layoffs and other personnel practices for government employes.

In a one-sentence order, the chief justice overturned a U.S. Court of Appeals ruling that had blocked the Office of Personnel Management from putting the revised rules into effect last Monday. Burger gave no explanation for his order, but an opinion outlining his reasoning is expected later.

Joseph A. Morris, general counsel for OPM, said the order appeared to allow the new rules to take effect immediately. "Legally, I would say that the regulations are in effect right now," Morris said.

The revised rules were drawn up by the Reagan administration in an attempt to put more emphasis on federal workers' performance and less on seniority. The regulations are expected to make it more difficult for employes to obtain regular pay raises and to weaken job security for longtime employes.

The revamped regulations, which have been vehemently opposed by unions representing federal employes, will affect longevity pay increases and reductions in force for 1.2 million white-collar workers, including about 360,000 in the Washington and Baltimore areas.

Congress twice has barred OPM from instituting the revised rules, but the latest congressional ban expired Monday. A renewed attempt to overturn the new regulations is expected later this month after Congress returns from its July 4 recess.

William J. Stone, assistant general counsel for the 700,000-member American Federation of Government Employees, said last night that the union had not decided whether to seek to appeal Burger's order to the full Supreme Court.

"We're disappointed," Stone said. "But we're still optimistic about ultimately prevailing on the merits, and we're awaiting hopefully favorable action by Congress." A legal challenge by two unions against the revised regulations is pending in U.S. District Court here.

Morris said that the revised regulations would initially have a relatively limited effect on most employes because of "safety valves" and a "built-in delay" in the rules. Federal agencies must draw up plans for carrying out the new pay and other procedures, Morris said.