The number of disciplinary suspensions from Prince George's County school dropped 25 per cent in the past school year, but the proportion of black students to white among those suspended rose slightly.

The drop in the number of suspensions from 17,513 in the 1975-76 school year to 12,997 resulted from "more parent contract" and from "Focusing on the students" problems rather than immediately suspending them," according to interviews with School Supt. Edward J. Feeney and several school principals.

The high proportion of blacks suspended - it rose to 58.3 per cent of all suspensions from 57 per cent in 1975-76 and 51 per cent the year before - has been a particularly sensitive issue and once prompted the county NAACP to sue the school system.

Peb Ali, director of the NAACP's suspension project, said yesterday. "These statistics aren't looking good to HEW or other funding agencies (which could cut off federal school aid under certain circumstances) . . . and they are going to have change."

School officials, who point to the drop in the total number of suspensions as a success in improving discipline, say the increase in the percentage of black suspensions is misleading because of dramatic shifts in the racial composition of the school system.

In the past school year the system had 143,498 students, 53,959 - 37.6 per cent - of them black.

John R. Aubuchion, county school spokesman, said the number of black students in the system increased by 7 per cent since the 1975-76 school year, while the number of white students decreased by 7.6 per cent.

He said black students as a group are faring better because only 8.6 per cent of all black students in the system were suspended in the past year compared to 11.1 per cent the year before.

The suit filed in 1974 by the NAACP's legal defense fund accusing the schools of using disciplinary powers to deprive black students of their right to education equal to that of white children wae settled out of court after officials agreed to set up fair guidelines governing suspensions. It was hoped that the guidelines, under which a student conduct code was adopted, would reduce the number of blacks suspended.

Last year when he suspension issue was raised. School board member Maureen K. Steinecke said: "There are too many suspensions, period. But that doesn't mean I'm opposed to suspending children. But junior high is the most difficult age for children and we have to find a better way to deal with them than to set them loose in shopping centers for a day or two."

Answering that concerns, Supt. Feeney promised to place high prioriy on reducing the suspension rates without relaxing disciplinary standards.

In junior high schools alone, the total number of suspensions were reduced from 11,773 to 7,365, a reduction of 37.4 per cent.

Dr. Feeney said "concern" still exists about the number of suspensions in the school system, but there is a "clear indication" that the school system is "moving in the right direction."