Fairfax County School Superintendent Robert R. Spillane has cut in half his budget recommendation for classroom computers because of a reduction in anticipated state aid and public criticism of his plan.

Gov. Gerald L. Baliles' proposed budget would give the county $4.4 million less than officials had anticipated. Spillane included the reduction in a revision of his proposed 1987 school budget, which the School Board is scheduled to vote on Feb. 19.

School officials cushioned the blow by changing the date for a one-time state payment, thereby lowering the anticipated reduction to $2.8 million, said Carl F. Juncker, assistant superintendent for financial services.

Spillane's proposed budget revision takes its biggest bite -- $2.4 million -- out of spending for new technology and computer staff. That includes a 50 percent reduction, $1.4 million, in spending for computers in the county's general, special and vocational education classes. The rest is in reductions for staff and computers for school offices.

Some PTA officials and computer experts told the School Board during budget hearings last week that the county should evaluate its existing use of computers in the classroom before going ahead with a more ambitious plan.

Spillane achieved enough reductions in his budget revision to add two new items to his proposed spending plan. One is $392,743 to speed up the opening of a the new Sully Elementary School in the Franklin Farms area of the county during the 1986-87 school year in accord with School Board orders.

The other, $304,480, would be added to the $750,000 already proposed for eight "special needs" intermediate schools and nine "special needs" high schools -- schools with large numbers of minority, transient or foreign-born students. The funds would allow for more teachers to reduce class sizes and for clerks.