The Prince George's County school board voted 7 to 2 last night to adopt a $271 million preliminary budget for next year, although some board members complained that the budget is unrealistic in view of the county's new property tax revenue ceiling.

The proposed budget, which now goes to County Executive Lawrence J. Hogan, is about $6 million higher than last year's and does not include wage increases being negotiated with 13,000 school employes. Those increases will bring the total increase in the budget to at least $15 million.

The budget approved last night also fails to include any savings that would result from school closings. More than 20 schools have been recommended for closing by community task forces or school officials, and budget planners estimate that $100,000 could be saved for each school closed.

Hogan, who has the authority along with the County Council to set the final figures for school spending, frequently has said that the increase approved by the board last night is impossible under TRIM, the voter-approved charter amendment that may limit the total county budget increase to less than $10 million according to some estimates.

Two board members agreed with Hogan. "I had hoped in view of the stark realities we would have been able to prioritize programs," said board member Susan B. Bieniasz.

"We have not. This budget does not deal with the requirements of the county budget under TRIM. The fact is that voters placed a cap on our money this year."

In three weeks of hearings and work sessions on the budget, the school board's only changes in the budget proposed by Superintendent Edward J. Feeney in December were to add almost $500,000 to expand programs for gifted students and add school guidance counselors.

"The budget is tight," said board member A. James Golato, at a work session early this week. "There's not much we can do. We're just puttering around."

"We've added programs," complained Bieniasz last night, "but the money for the increases we've proposed just isn't there."

Bieniasz and other board members predicted that the real budget work of the school board will begin in several months, when the school budget is returned by the county council after being cut.

Hogan and the council have the authority to make cuts in general areas of the school budget, and the board members then must decide which specific programs will be reduced.

Already, Hogan has sent several lists of questions to Feeney about items in the budget he is considering cutting. Hogan has asked Feeney for details of the schools' computer services, buses and elementary health aide services, among other programs.

"The real problem is ahead," Feeney said in an interview. "There is not a parent who voted for TRIM who believes it will impact their child's program. When it does they are going to be very unhappy."