The District of Columbia's budget crunch will force the school system to lay off an additional 200 teachers and 200 other employes, bringing the total number of school system layoffs this year to 1,100 employes, School Superintendent Vincent E. Reed disclosed yesterday.

Among those expected to go, Reed said, are reading and mathematics specialists and other special teachers, along with 45 assistant principals and 52 administrators in the school system's central office.

Reed said the system originally planned to cut about 607 teachers, 394 of whom already have received layoff notices.But because the school system must cut an additional $8 million this fiscal year, Reed said, the teacher layoffs now are expected to total about 800 from a teaching staff of 6,600.

The new batch of school layoffs came to light as Mayor Marion Barry went to Capitol Hill to seek support for a new fiscal 1981 budget that would trim 2,700 jobs from the overall city payroll.

One proposal, to drop 204 uniformed officers from the police department after Oct. 1, got a hostile reception from key members of the House D.C. Appropriations subcommittee who heard the mayor testify.

"The people who pay the taxes . . . have a right to walk the streets," Rep. William H. Natcher (D-Ky.), the subcommittee's senior member and a former chairman, told Barry. "I think it [the police layoff proposal] is a serious mistake . . . I wouldn't reduce the police department one officer if I were in charge of it."

Rep. Carl D. Pursell (R-Mich.), the panel's ranking minority member, agreed and suggested that the subcommittee add language to the city's budget bill requiring that the police force be kept at full strength.

Under Natcher's leadership the subcommittee built the police department up to a peak strength of 5,100 officers in the early 1970s and opposed later city proposals to cut it as the crime rate dropped.

The force now has 3,949 uniformed officers, a figure that would drop to 3,676 after Oct. 1 because of resignations, retirements and 204 layoffs, the department's budget director, Inspector Isaac Fulwood, testified yesterday. Attrition is expected to bring the force down to 3,476 officers by Oct. 1, 1981.

Barry, who advocated cutting the force as a City Council member, insisted that "our thrust today is budgetary."

In an attempt to deflect opposition to the police cuts, Barry disclosed that the school system would have to lay off even more employes. But no subcommittee member asked him to elaborate on the school cuts.

Barry was in the witness chair for 2 1/2 hours as the subcommittee, headed by Rep. Julian C. Dixon (D-Calif.), opened hearings into the budget revisions, which would slash $61 million from a long list of city programs.

The cuts -- including those in the school system and police department -- are needed, the mayor said, so the city can absorb higher costs for energy, payrolls, pensions and other items and still have a balanced operating budget of $1.5 billion. Barry said the precariously balanced budget depends on the city's getting the full authorized federal payment of $300 million as the U.S. share of city operations.

The city also has pending before Congress a supplemental budget request of $61.8 million in federal funds for the current fiscal year, which ends Sept. 30. That request is before the Senate, where only $45.3 million has been proposed, and was not discussed at yesterday's hearing.

Barry told the subcommittee that he is working with the city's financial advisers on a plan to erase an accumulated deficit of $284 million that was disclosed in April in a report of an audit of the city's books.

The auditors found that the city owes that amount in various debts and accounts that it ultimately may have to pay off.

Barry did not know it as he was testifying, but the subcommittee had just received a letter from the General Accounting Office -- the auditing arm of Congress -- saying flatly that "the District's financial condition is not as bleak as this [$284 million] amont would lead one to believe."

The GAO report was first sought by Rep. Eldon Rudd (R-Ariz.), a subcommittee member who suggested the large figure was part of a "game plan" by the city to justify a large congressional appropriation or being permitted by Congress to sell bonds to pay off the debt.

In the report, the GAO said that nearly $195 million of the accumulated deficit was made up of items that recur each year and should not be counted as long-term debt or items the city will never have to pay in a lump sum that would cause financial distress.

City budget director Gladys Mack, who learned of the GAO report after Barry departed, said officials would have to review it before commenting.

Under city budget procedures, the entire city budget -- including the school system's -- is reviewed and appropriated in considerable detail by Congress. But the school system has considerable autonomy from the mayor and his administration, and can decide on its own how budget reductions will be made.

The new reductions would cut an additional $8 million from the current budget and $35 million from the originally proposed $252 million in operating funds in fiscal 1981, Reed said.

School officials and other city department heads are expected to testify next week.