Representatives of two community groups and a teacher association urged the Fairfax County School Board last night not to agree to continued ceilings on school spending fixed in advance of planning for the county education budget.

The board's agenda included a discussion of a resolution, adopted Monday by the County Board of Supervisors, urging the School Board to propose a school budget based on increases in the cost of living, county population and school enrollment. The resolution is similar to ones adopted every year since 1981, except that it does not specify what the cap on spending should be.

The resolution was sent to the School Board for its concurrence. Last night, the School Board decided to postpone a vote from Nov. 7 to Nov. 21 to permit greater public discussion.

Supporters argue that it would encourage fiscal responsibility and would not shrink the county's commitment to good schools. Opponents contend that a cap made sense in 1981, when one was first adopted during a national recession, but imposes arbitrary limits during better times when schools have many pressing needs.

Last night, the proposed resolution was opposed by the 50,000-member county Council of PTAs, the Fairfax area League of Women Voters and the Fairfax Education Association, representing teachers and other school employes.

Kevin H. Bell, president of the PTA council, said he was told by a member of the Board of Supervisors that even though the resolution does not specify how much the school budget will grow, the increase permitted for fiscal 1987 will be 6.5 percent.

Barbara Shanahan, League of Women Voters president, said that if the School Board approves such a vaguely worded resolution, it "is basically agreeing to use guidelines without knowing what they are."

Donna Caudill, president of the Fairfax Education Association, said a vote for the resolution would be a vote to "pay lip service to quality and dance to the play of the supervisors' strings." She received prolonged applause after her remarks from a large crowd in the Jackson Intermediate School auditorium who were present for an awards program.

In other business, the School Board voted to name McLean High School Principal Murriel F. Price one of four area superintendents. Price will oversee Area 3, which includes schools in the McLean-Vienna section of the county. Before coming to McLean High School, Price was principal of Herndon High School. He succeeds Patsy Costolo, who is resigning at the end of this month after only four months on the job.