Four members of the NAACP's national board held a six-hour hearing yesterday on whether to reinstate William R. Martin as president of the organization's Prince George's County branch, but adjourned without making a ruling on Martin's case.

Martin was suspended by national NAACP Chairman Benjamin L. Hooks two months ago after Martin initialed a controversial agreement with the school board chairman to curtail busing in the county's integrated neighborhoods.

Yesterday's hearing at a Hillcrest Heights motel was the crucial first step in a series of NAACP actions on Martin's fate.

"I think it's a tossup" on reinstatement, said Martin, who underwent questioning - some of it pointed - for more than an hour at the closed-door hearing. Whatever the outcome, Martin said he will continue his fight: "I may reactivate the Citizens for Quality Eduction, a committee that worked for me in 1973," when he was running for election to the school board.

The question under discussion yesterday was whether Martin violated NAACP policy by failing to consult his executive board before initialing the "memorandum of understanding" with the school board.

But the underlying issue is more sensitive: whether black and white children should be exempted from busing if their neighborhoods are already integrated.

Noting that 96 of the county's 226 elementary schools have more black students than white, Otis Ducker, who testified for Martin yesterday, said, "We have to recognize one-race schools for what they are . . . we already have them. We should take steps to assure quality education."

Calling white flight a "big concern," Ducker said, "If we don't do something, this county's going to turn all black."

But the Rev. Perry A. Smith III, another witness, opposed the busing cutbacks Martin sanctioned. "Quality education is the central issue. We have to be certain that we have quality education for every child. If that requires busing, we should have busing. There's no such entity as a 'neighborhood school,'" he said.

That underlying issue was apparently not debated in yesterday's hearing, which was closed to the press. According to participants, the hearing focused on whether Martin violated NAACP procedures in negotiating with the school board by himself. CAPTION: Picture, WILLIAM R. MARTIN . . . "I think it's a tossup"