D.C. Mayor Marion Barry said yesterday he would give the Board of Education most of the funds it is seeking for the coming fiscal year. But to do that, he will have to postpone an important step in his highly touted plan to retire the city's accumulated debt.

The mayor's action appeared designed to defuse his longstanding feud with the school board over finances and to show his support for public education, as he prepares to run for reelection this year.

He emerged from a 90-minute meeting with school board officials yesterday proclaiming "a new era of cooperation."

Barry said he would add $14.3 million to his original budget proposal of $249.5 million for the schools, bringing the total to $263.8 million. The school board requested $289 million, but Board President Eugene Kinlow said after the meeting that the mayor "is moving in the right direction."

In order to increase spending for schools, Barry said he would defer setting aside $10 million to begin paying off a portion of the city's massive $388 million accumulated debt. The rest of the money would come from a new $20 million pool that will be put at the mayor's disposal next year.

The mayor's action signals a significant retreat from the financial recovery plan he unveiled in July 1980. At the time, he said the plan would gradually eliminate the debt, avert future cash-flow problems and end the city's dependence on the U.S. Treasury for long-term borrowing for building projects.

Under the plan, the city would set aside $10 million a year until it had eliminated about $204 million of so-called "non-cash" debts, which include accrued interest owed to the Treasury and annual leave time owed to city employes.

The remaining $184 million of the debt, including unpaid bills and money owed the Federal Bureau of Prisons and St. Elizabeths Hospital for housing D.C. residents, was to be refinanced last year through sale of general obligation bonds.

But the bonding measure ran into stiff opposition last year in the House of Representatives, and prospects for its revival this year appear slim. With Barry now reneging on his pledge to set aside $10 million a year, the mayor's overall strategy appears to have collapsed.

Barry insisted yesterday that his plan still was "active." But he concluded that school system needs took precedence over his desire to eliminate the "non-cash" portion of the debt.

"It represents a choice between $10 million to retire the sins of the past or $10 million to help the future," Barry said. "It's for the children. It's important."

Barry said the board could use the additional funds to resume the driver's education program that lost its funding last year, improve the basic- and special-education curricula and offset anticipated cuts in federal grants.

Despite a steady decline in pupil enrollment, Barry said there would be sufficient funds next year to maintain the current number of teachers.

Moreover, he said there would be sufficient funds in the 1982 and 1983 budgets to cover 5 percent-a-year increases in teachers' salaries, which are being renegotiated. About $22 million would be budgeted in fiscal 1983 for pay increases, he said, although unions are seeking substantially more.

Kinlow said that while he was encouraged by the revised plan, it still offered only a modest improvement over the school's current budget of $253 million.

"It's a bare-bones budget, and that's not the way to treat education," Kinlow said. "There's no way all the things Barry proposes can be done with a $10 million increase over the current budget. . . . We'll do the best we can to try to get the City Council to move some more money around."

City Council member Betty Ann Kane (D-At Large), who is seeking election as mayor this year, described Barry's revised plan as "another election-year shell game" that would be inadequate to cover the probable pay increase.

"People who really know the school system know that when the pay increases are finally factored in what the mayor is proposing is really a cut from this year's spending level ," said Kane, a former school board member.

But Barry contended that his revised budget proposal was sufficient "to buy enough time so that the new Board of Education will have an opportunity to roll up its sleeves and tackle some of the tough cost-saving decisions that can no longer be ignored."

The mayor argued that the school board in the past has devoted too large a share of the budget to non-teaching activities, and must alter its spending patterns. He noted that under the current budget 36 percent of spending is for non-instructional support services.

"We are concerned about the non-classroom costs, and the need to reduce them and turn that money back into the classroom," he said.

Barry announced his revised plan after meeting in his office with Kinlow, School Superintendent Floretta D. McKenzie and about 10 other school officials.