Presidents of traditionally black colleges meeting in Washington last week found themselves doing a delicate balancing act with the Reagan administration.

On one hand, President Reagan signed an executive order last year setting up a government-wide plan to help black colleges and has proposed to increase funding for aid to "developing institutions." And Vice President Bush chaired a January meeting in which black college leaders sought grants from corporate executives.

On the other, Reagan has proposed cuts in student aid that the black presidents say would devastate their schools. Some have estimated enrollments would be cut by a third.

A recent policy statement by the National Association for Equal Opportunity in Higher Education illustrates the group's diplomatic tack.

It starts on an upbeat note, expressing "pleasure" at the administration's proposed $5 million increase in the $130 million for "developing institutions."

It gets around to the "devastating impact" of the student aid cuts several paragraphs later.

Then it asserts that the cuts would make the increases in institutional aid "fade into insignificance."

Samuel Myers, executive director of NAFEO, said the members had been willing to wait a while to see if the Reagan rhetoric produced tangible results. "Now one by one he's losing them. They are not believing him."

Some no longer see any reason to be diplomatic.

Lionel H. Newsom, head of Central State University, in Wilberforce, Ohio, for instance, was particularly blunt in an interview Thursday.

"President Reagan hasn't done a damn thing he said he was going to do....There's been nothing but talk. He hasn't put any money where his mouth is," Newsom said. Of the Bush meeting, he added, "That was nothing but a bunch of bull...a farce. We haven't seen a thing from it."

The 111 traditionally black schools enroll about 200,000 students, about one-sixth of the blacks in college. But their leaders say they produce about half of the black college graduates and many of the black community's professional and political leaders.

W.A. McMillan, president of Rust College in Holly Springs, Miss., said there seemed to be "a degree of psychology" in the group's policy statement--a desire to maintain ties to the administration.

He said black college leaders were heartened last year when Reagan signed the executive order calling for a government-wide initiative to aid black colleges. "But we haven't seen anything on that," he said.

"We applaud the verbosity" of the administration's statements, McMillan added. "But the reality of the situation is we see nothing on the horizon from private industry or the government that would make up for student aid cuts."

The $5 million more in "developing institutions" money, which provides grants for struggling colleges to improve faculty and programs, is "a drop in the bucket" compared to the threatened loss in student aid, he said.

Every one of Rust's 750 students gets federal aid. "I'd sure rather see my tax dollars go to educate a student than buy a missile," he said.

Several of the black college leaders said they are encouraged by signs that Congress seems unlikely to pass all of Reagan's proposed cuts.

However, Elias Blake Jr., president of Clark College in Atlanta, said he is still cautious because the cuts haven't been totally blocked yet. He remembers the administration's success last year in lumping the whole budget into one up-or-down vote.