The main obstacle to black economic development is not discrimination but a lack of marketable skills and education, economist Andrew F. Brimmer said yesterday.

Brimmer, a former member of the Federal Reserve Board, said job preparation is best addressed by blacks and not the government.

"Certain problems are not a matter of circumstance but a matter of choice for black people," he said in a speech prepared for the Joint Center for Political Studies' eighth annual dinner. He cited the high birthrate among black teen-agers and the frequency with which young black men become frustrated and stop seeking jobs.

"The high birthrate is not something for the government to correct," he said. "This is not discrimination. This is behavior."

Brimmer noted that in the last two years blacks had made "moderate" economic progress after two "severe recessions" in the last five years. But he warned that poor blacks are not sharing in the economic progress and "the schism that has been evident in the black community between those at the bottom of the income scale and those who are better off has gotten even deeper."

Brimmer said that among black families headed by single women, the poverty rate in 1983 was 53.8 percent, compared with 28.3 percent for white families headed by single women. He said black families led by single women, which are 4.6 percent of the population, accounted for 29.9 percent of all public assistance and supplemental income in 1983.

Brimmer stressed that he was not dismissing the idea that discrimination is a barrier to advancement. "However," he said, "we have reached the point where the cutting edge is not discrimination but capability, capacity, marketability."

While absolving the government of responsibility for some key black problems, Brimmer criticized the Reagan administration for reversing support for affirmative action and for proposing cuts in student aid.

To spur the employment of young black males, Brimmer supported a two-tier minimum wage. That idea, proposed by the Reagan administration, has run into stiff opposition from those who argue it would induce employers to fire adults and hire youths at the lower wage.

Brimmer said that on-the-job training is a fact of American life and that for most young people the $3.35 minimum wage "greatly exceeds their production." He proposed that a second minimum wage be set at 75 to 80 percent of the current minimum wage, or around $2.60.