Fifteen teachers of disadvantaged children in Perry County, Miss., were laid off yesterday as nearly $200,000 in annual federal education funds were cut off following a racial discrimination finding against the school board.

Justice Department attorneys are investigating whether other federal funds for the district, such as the federal portion of the school lunch program, should be cut.

The Reagan administration informed the Perry County board a month ago that federal aid would be terminated April 5 because it had failed to reach a settlement with two coaches fired in 1978 after complaints by a board member that they weren't playing enough white players on the district's New Augusta high school basketball team.

Last year, following an enforcement proceeding started by the Carter administration, a Department of Education administrative law judge found the board guilty of discrimination against the coaches and the team's black players. It was the first time in more than a decade that a school's federal funds have been cut off.

Mardis Walters, the local coordinator of the Title I program, which provides for children with academic problems, said the layoffs mean that 564 elementary students, a majority white, will be left without extra reading and math instruction. There are about 800 elementary students in the 1,500-student system, which is about two-thirds white, according to the local superintendent's office.

T. Jack Riley, attorney for the school board, said the county is losing about 20 percent of its $1 million a year budget. The Title I program is $186,000 a year and small slices of handicapped and vocational funds bring the total loss to about $200,000. But only the Title I program is being stopped, he said. "The board felt it could carry on the other programs."

A Justice Department official said the civil rights division is examining $300,000 the U.S. Forest Service pays the district in lieu of taxes from a national forest in the county as well as school lunch and other federal money Perry County receives to see if there are grounds for canceling all payments.

"It's really sad," said Walters, Perry County's Title I coordinator. "The children feel lost. The regular teachers are upset. The Title I people all lost their jobs. It's had a great impact on this county."