D.C. school board member Bob Boyd, the Ward 6 representative since 1983 and one of the leading education activists in the city, announced his resignation yesterday.

Boyd, saying he believed the 11-member board is "in good hands," told his colleagues that he has accepted a job as an assistant to Rep. Mike Espy (D-Miss.). Elected in 1986, Espy is the first black member of Mississippi's House delegation since Reconstruction.

Boyd said he will leave his board seat Jan. 31 and move to Mississippi to begin work with Espy.

"After seven years, I'm worn out, but I'm not leaving with any sense of despair," Boyd said. "The future is brighter now for our schools than it has been in some time, despite the clouds over us now."

Once Boyd leaves, the board must appoint an interim successor until his term expires in 1992. Boyd said he hopes the board will pressure the city's Board of Elections to hold a special election next year.

During his two terms, Boyd has gained a reputation among his colleagues as one of the board's hardest workers and one of its strongest advocates for change in the 80,000-student school system.

One of the board's three white members, Boyd has retained strong support among black voters in the ward, which stretches from Capitol Hill to Anacostia.

"We're losing a fine board member who always has supported us," said Ralph Neal, principal of Eastern High School in Ward 6. "Any time I called on him for help, he came without hesitation."

During his tenure, Boyd has been one of the few board members who worked directly with students.

He was a chaperone for Eastern's choir on its award-winning trip to Vienna two years ago and paid several students' travel expenses.

He also helped Eastern start student-of-the-month luncheons, and he has taught at Kramer Junior High in Anacostia.

But at times some of his decisions have been controversial.

Last spring, Boyd said that four Ward 6 schools with low enrollment should be closed, a move that provoked fury among some parents who derided him as a racist.

He also voted to fire Superintendent Andrew E. Jenkins last month.

Boyd, 45, is a writer who grew up in Mississippi and was active in the civil rights movement.

He also was a founder of the local schools advocacy group Parents United.