The Pentagon is preparing a fiscal 1983 supplemental budget request asking Congress to reverse last year's votes and provide money for MX and Pershing II missiles, officials said yesterday.

The Defense Department also is drafting separate legislation to take money from many of the weapons programs added by lawmakers to the military budget in the closing days of the last Congress.

President Reagan is expected to tip his hand Jan. 31 about the politically explosive request for more defense money for the current fiscal year when he submits to Congress his fiscal 1984 budget proposal. That will include new estimates of how much will be spent on national defense in the current fiscal year.

Administration officials said the new totals will show the supplemental request now in prospect but not yet in final form. This would sharpen the guns-vs.-butter debate that raged in the last Congress because Reagan would be asking not only for more money for the coming fiscal year but also for the current one while seeking to kill some pet congressional projects.

This administration plan means Defense Secretary Caspar W. Weinberger will soon be fighting three battles simultaneously on Capitol Hill: the fiscal 1983 supplemental request, the sought-after cutbacks in spending, and the new fiscal 1984 defense budget.

White House and Pentagon strategy, administration officials added, is to withhold details of exactly what would be bought with the extra money for fear of becoming embroiled in another military budget battle before the administration can prepare new arguments for such controversial weapons as the MX and Pershing.

Under one draft proposal, $1.3 billion in supplemental fiscal 1983 funds would be added for the MX in hopes of keeping the missile on its original schedule, which called for initial deployment in 1986.

Pentagon officials have told their counterparts in the Office of Management and Budget that the extra money is vital and have promised to reduce the impact on the deficit by seeking congressional authority to forgo spending on other previously approved projects.

To improve their chances of congressional approval for the MX, Reagan and Weinberger have appointed a commission to review various basing schemes for the 10-warhead land missile. When its report, due next month, is in hand, Reagan will make a new pitch for money to produce and deploy MX.

After last year's heated defense debate, Congress denied the $966 million Pentagon request to produce the first five MXs and held off $560 million in MX research funds until both chambers passed a concurrent resolution approving the basing scheme.

Reagan and Weinberger consider the MX and Pershing II vital to establishing credibility around the world in the face of the Soviet threat. Soviet leaders have launched a campaign to keep the first Pershings from being deployed in West Germany in December as scheduled.

Last year, Congress deleted $493.3 million for producing Pershing II but said it would reconsider that action if the testing record of the nuclear-tipped battlefield missile improved. An apparently successful flight test of the missile took place last week, and the testing continues.

The Pentagon hit lists of projects approved by Congress involves cutbacks called rescissions. Congress must approve these within 45 days before the Pentagon can deny the projects funding.

"Almost everything Congress added to our budget last year is on the rescission list," one defense official said.

"Do these guys realize what they're in for? " a congressional staffer asked when he learned of the one-two punch of supplemental requests and a rescission list.

At a time when the president's entire economic program is under the most serious challenge yet, Reagan and Weinberger will be taking their case to a Republican-controlled Senate and a House in which Democrats gained 26 seats in the elections last November.

Although Pentagon officials stressed that the content and timing of the supplemental request and hit list are uncertain, these actions could be, no matter when they are submitted to Congress, a double whammy for some powerful lawmakers.

For example, Rep. Joseph P. Addabbo (D-N.Y.), chairman of the House Appropriations subcommittee on defense, pushed successfully last year for adding money to the Pentagon budget for the Air Force A10 antitank plane, made by Fairchild Industries in Hagerstown and on Addabbo's home ground of Long Island. He also led the fight against the MX.

If the A10 is on the final hit list, despite Reagan's expressed support of the plane as he was rounding up votes for the highways-gasoline tax bill, the Pentagon would be asking permission to take money from a program Addabbo championed to give it to one he opposed.

Other congressional add-ons to the Pentagon budget have the same double-whammy potential. Two examples are the $60 million for the McDonnell Douglas C17 transport plane and $588.7 million to buy new engines for the Boeing KC135 aerial tankers.

From the Pentagon viewpoint, the president's plan for rearming the nation cannot be allowed to falter by default.

Last year's battles over MX and Pershing II must be fought anew, in this view, in light of what defense officials see as pressing realities, including an unrelenting Soviet buildup and a concerted attempt to tear up the North Atlantic Treaty Organization over the issue of theater nuclear weapons.

Reagan's biggest single setback last year on defense was denial of MX production money after his "Dense Pack" deployment scheme was unveiled and widely ridiculed in Congress. Dense Pack envisions burying 100 MX missiles so closely together in the Wyoming prairie that attacking Soviet warheads would knock each other out trying to destroy the silos.

President Carter's recommendation, which Reagan ridiculed during the 1980 campaign, called for hauling 200 missiles among 4,600 concrete garages spread around the valleys of Nevada and Utah.

The presidential commission on MX, which lost some political clout last week when former defense secretary Harold Brown decided he could not remain on it because of legal problems arising from his private consulting work, is expected to look closely at digging more than 100 holes for the 100 MX missiles to provide some of the advantages of the Carter scheme.