The D.C. school board yesterday approved a $336,454,100 budget for the fiscal year beginning Oct. 1, 1983, that school superintendent Floretta D. McKenzie said will "stabilize, maintain and improve" instructional services.

The $336,454,100 figure represents a 7.2 percent increase over the fiscal 1983 budget of $313,861,700. That budget still is pending before Congress and has yet to be approved.

Included in the fiscal 1984 budget are plans to cut 126 teacher positions, but a further projected decline in enrollment, from 91,300 to about 89,000 will mean that teacher-student ratios will remain about the same, school officials said.

The school board is required by federal law to approve the fiscal 1984 budget a year in advance. The fiscal year begins on Oct. 1.

The fiscal 1984 budget adds no new programs or teacher hirings, but is designed to maintain several new programs planned for the current school year, officials said.

"This increase is reflective of a 'hold-the-line' budget that includes only those costs necessary to stabilize, maintain and improve existing services within the school system," said McKenzie.

Some of the $22.6 million increase in the budget is to provide salary increases that will give teachers an eight percent pay raise. The budget also adds an additional $142,400 for bilingual education, and transfers money to fund 49 aides to help reduce truancy at the junior and senior high school level.

The fiscal 1984 budget also must be approved by Congress, which will take it up next year.