President Reagan's civil service chief went to Capitol Hill yesterday, in a government-owned Oldsmobile diesel, to outline the administration's plans for "reforming" the government's package of pay and fringe benefits.

Judging from the reception he got, he may need an Army battle tank armed with missiles next time he makes the trip.

Donald J. Devine, head of the Office of Personnel Management, took the administration proposal to the hearing room of the House Post Office-Civil Service Committee. He was surrounded by a standing-room only crowd made up of mostly hostile but interested civil servants and union lobbyists, with observers from the press and from other interested committees.

Devine told the congressional unit -- which is supposed to handle federal personnel legislation -- that the administration would like its permission to cancel this year's federal pay raise and next year's retiree raise, totally revamp the government retirement program and put more stick and less carrot in the system to decide who gets seniority raises and who does not.

The very cool reception he got is important because the committee can do a lot -- if it chooses -- to delay, modify or kill any of the reforms the White House is pushing.

Devine said the major civil service shakeups are designed to make government more like the private sector; to increase incentives for top-drawer workers and to convince the public that working for the government is not a gravy train.

He irked Democrats, who dominate the committee, by saying the proposals are a natural extension of the Civil Service Reform Act, which he described as one of the major accomplishments of President Carter.

Rep. Mary Rose Oakar (D-Ohio) who chairs the compensation and employe benefits subcommittee (which sponsored the meeting) said she thought Devine was guilty of "the sin of omission" in some of the charts, documents and data he brought to support his thesis that Uncle Sam is one of the nation's most generous employers.

Rep. Steny Hoyer (D-Md.) lectured Devine (a former University of Maryland professor) on the antifederal worker bias of the administration, and said federal employes do not feel that the OPM "represents their best interests."

Devine got some moral and verbal support from fellow Republicans Connie Mack (Fla.) and William E. Dannemployer (Calif.), but none at all from Rep. Frank Wolf of Virginia, who represents large numbers of federal workers and retirees.

Wolf said the CS Reform Act -- which Devine felt was the bright spot of the Carter years -- is "a shambles" that Congress should admit was a "mistake."

Wolf said the Reagan administration's attack on the civil service is an example of "the law of the jungle.... You go after the smallest boy, the weakest girl in the school yard." He said that the relatively small number of federal workers (2.8 million) and retirees (1.8 million) makes them fair game for politicians.

He proposed that the administration put its "reforms" on ice and appoint a commission to study the entire federal personnel system and come up with recommendations that would be fair without destroying the government's ability to attract and keep good people.

Wolf suggested that former President Ford head the commission, which he said should also include former Post Office-Civil Service Committee Chairman David Henderson (D-N.C.), and retired CBS anchorman Walter Cronkite, whom polls have shown to be one of the most believable men in America.

Devine said the proposals the administration is making have been studied, and that time is running out -- particularly for the federal retirement system, which he said has a debt of half a trillion dollars. Unless workers pay more into the system, and are discouraged from taking early retirement, the system will be in real trouble, he said.

But members of the key committee and subcommittee made it clear yesterday that the president's plan isn't going through them, and that if it becomes part of the budget reconciliation process they will attempt to kill it.