R. Calvin Lockridge, president of the District of Columbia School Board, yesterday delivered his most slashing attack to date on Mayor Marion Barry, accusing him of using a hatchet to deliver "a Dr. Frankenstein amputation" of the school budget.

Appearing at a budget hearing by the City Council, Lockridge used such words as "disastrous . . . skulduggery . . . dirty work . . . devastation" to describe the mayor's proposed cuts in school spending.

Lockridge also charged that "this city is still paying for . . . mismanagement" of the schools while Barry was president of the school board from 1972 to 1974.

Barry "is now mismanaging the city with the same unique brand of leadership he brought to the Board of Education and, God forbid, any day now it is likely the city will default," Lockridge asserted.

Lockridge has been at odds with Barry since becoming a school board member in 1977 and particularly since he became board president in January. The months since have been dominated by the District's growing budget crisis and Barry's efforts to cut city spending.

Lockridge has criticized Barry before in letters and public statements. But yesterday's six-page prepared statement to the City Council was the sharpest criticism he has leveled.

Lockridge's target was a proposal by Barry that the school system cut its spending by up to $39 million in fiscal 1981, which begins next Oct. 1, below the proposed $252.2 million budget originally sent to Congress in January. The new reduction would be part of Barry's amended budget for all city agencies that is designed to pay higher costs of energy and pensions while trimming numerous city programs.

Lockridge and other members of the school board appearing before the council yesterday resisted Barry's proposed cuts.

"Frankly," Lockridge told the council members, "I suspect some of you may not care . . . in order to bail the city out of problems with fiscal mismanagement, some of you may find it easy and politically palatable to take money from children to pay for the problems which now exist."

Lockridge said District school spending at $2,294 per pupil in 1979 was next to the lowest among jurisdictions he listed in the Washington area. Prince George's County, at $2,176, was the lowest listed, while Alexandria, with $3,030, was the highest.

Lockridge also sharply attacked The Washington Post, calling it "one of . . . the real masters of this city."

Lockridge told a reporter after his testimony that his charge of mismanagement by Barry of the school system was made because school employment was increased sharply during the mayor's term as board president and numerous administrators were shifted from temporary to permanent assignments. It is these same people Barry now wants the school board to drop from its payroll, Lockridge said.

Lockridge said his criticism of The Post was based on a recent editorial that accused the school system of overspending its current budget. He contended that the editorial was based on inaccurate information supplied by the city's new computerized financial management office.

Council member Nadine P. Winter (D-Ward 6) challenged Lockridge's contention that council members do not care about the schools. She said the council is getting a lot of conflicting pressures on where to cut the budget. "We are being lobbied by every group in the city," she said. "People are afraid crime will go up . . ."

John A. Wilson (D-Ward 2) asked plaintively what suggestion school officials might have for cutting other programs in order to get their own money. "I don't know where the money is going to come from at this point . . . I really don't know how we're going to do it."