The new budget President Reagan will send to Congress next week calls for deep new cuts in Medicaid, food stamps, subsidized housing, welfare, aid to education and many other of the basic federal social programs, according to a partial draft of the budget obtained by The Washington Post.

Judging by this draft--which is theoretically subject to additional revisions, though officials say none are being made--President Reagan has decided to reopen nearly all the fiercest budget battles that he fought last spring, including many that he lost.

For example, the new budget calls for wiping out the Economic Development Administration, a popular public works program that will provide localities with $198 million in the current fiscal year, which was saved last year largely by moderate Republicans in the House.

The budget also contemplates cuts in the future cost of retirement benefits for federal civilian and military employes and deep future cuts in the Medicare program for the elderly and disabled. The Medicare cut would amount to $16 billion a year by fiscal 1987, a much larger sum than previous reports had suggested the administration was aiming for in this costly program.

The documents obtained by The Post say that under the 1983 budget federal aid to state and local governments would be kept at about the level of 1974 in terms of purchasing power. That is about the same level as this year.

The documents also say that many of the new budget cuts would be achieved by creating eight new block grants in which existing federal programs would be consolidated and then funded through grants to the states. These grants would be considerably lower--as much as 30 to 75 percent--than the current level of funding for the specific programs involved.

Such cuts, if enacted by Congress, would dramatically shrink a wide range of federal programs before they would be turned over entirely to the states under Reagan's proposed New Federalism program.

However, leading members of Congress have already said publicly that the House and Senate are unlikely to approve anything like the reductions Reagan will propose in this new budget.

Many of the cuts outlined in the draft budget documents have been previously reported, often without precise figures. This is the first time the total impact of the administration's proposals for 1983 can be seen in one place. The budget to be unveiled formally next week will propose these cuts:

* $2 billion from the Medicaid program in which states and the federal government jointly pay health care costs for the poor. This would represent about a 10 percent reduction.

* $2.4 billion from the food stamp program, the government's second costliest welfare program (Medicaid is first).

* The termination of all new commitments under the government's subsidized housing programs. The new budget calls for expenditures of $3.8 billion on these programs for fiscal 1983, which is money committed in earlier years, but would not permit any new projects.

* $1.2 billion from the main cash welfare program, Aid to Families with Dependent Children. The president will propose reducing the federal share of AFDC expenditures from $8 billion in the current fiscal year to $5.1 billion next year, a reduction of 36 percent at a time when welfare rolls are growing because of poor economic conditions.

* $1.4 billion from federal aid for elementary, secondary and vocational education, a cut of 23 percent. Overall, the new budget will propose cutting aid to education by nearly a third, and aid for vocational education by nearly half.

* $500 million in savings on the federal civil servants' retirement program. The documents obtained by The Post do not explain how the administration will propose to reduce the costs of civil service retirement, but they show that by 1987 the White House hopes to have accomplished savings on these pensions totaling $1.9 billion a year.

* $2.2 billion from other government retirement programs, $2 billion from the railroad retirement fund. The president will also propose changing military retirement pay to save $100 million next year and more in later years.

* $600 million--or 16 percent --from federal aid for urban mass transportation. The president will propose eliminating all federal aid for new construction of mass transit systems and will ask to phase out all operating subsidies over the next three years.

The president's budget includes many other cuts, and freezes many programs at current spending levels--the federal highway program, for example.

On the big entitlement programs, according to this draft document, Reagan will propose total reductions of $11.8 billion for fiscal 1983, rising quickly to $16.5 billion in 1984 and $33 billion in 1987. This does not include any cuts in the Social Security program, the largest of the entitlements, which is not mentioned in this year's budget cuts.

The draft documents obtained by The Post outline eight new block grants to consolidate existing categorical grant programs and then fund them at significantly lower levels. The president also proposes adding to four existing block grants some programs that Congress refused to include in them last year. One of these is the nutrition program for women, infants and children (WIC), which the president suggests cutting by about one fourth.

The eight new block grants the president proposes would cover federal programs for employment and training, vocational and adult education, education for the handicapped, rehabilitation services, child welfare, energy and emergency assistance, rental rehabilitation and the administration of welfare programs.

In each of these cases, Reagan will propose overall spending markedly lower than the budget authority given to the categorical grant programs that these block grants would replace.

For example, the rental rehabilitation grant would substitute for the existing Section 8 rehabilitation program and a loan fund that are now funded at a level of $612 million. But Reagan proposes allocating $150 million to the new block grant.

A child welfare block grant that Reagan will propose would combine programs for foster care, adoption assistance and others. The president's block grant would be $65 million less than the $445 million earmarked for the affected programs in the current budget.

A block grant for employment and training would incorporate the four remaining programs under the Comprehensive Employment and Training Act, but would fund them at nearly 20 percent less than those programs now receive. The change would eliminate salaries paid to persons enrolled in job training programs.