On the eve of the 25th anniversary of the Supreme Court's historic decision banning racially segregated schools, National Urban League president Vernon E. Jordan Jr. declared yesterday that "the illusion of black progress is just that - a myth, a lie."

In a stinging indictment of American society and the way it treats blacks, Jordan said that for millions of blacks the promise that the high court's ruling would bring a better life has evaporated.

"Their needs have been ignored, their aspirations trampled upon and their desire for equal opportunity scorned," Jordan said at a Howard Law School symposium commemorating the 25th anniversary of the Brown vs. Board of Education decision.

"An indifferent nation has traveled a long road since Brown," Jordan said, "but it is a road that leads not to equality but to Bakke," a reference to last year's Supreme Court decision limiting the type of affirmative action programs that can be used to benefit minorities.

"The path from Brown to Bakke is a path of reaction and of callous neglect of the best interests of both the nation and its black poor," Jordan said.

"The plight of the black poor has been met with indifference, even hostility," Jordan said. "The Second Reconstruction ended before it had completed its work. It ended with the slogan 'benign neglect.' And today we hear similar slogans-'The Era of Limits' and 'The Era of New Realities.' But in the end they all boil down to the same thing-malign neglect."

Citing education, income and job statistics, Jordan said that contrary to popular belief black Americans are falling farther behind whites than they were at the time of the Brown decision or even compared to just a few years ago.

He said that the black student drop-out rate is "still double the white rate" and that proportionate to their numbers, three times as many black students are behind the grade level for their age, Jordan said that even the well-publicized figures showing that more blacks are attending college "hide the fact that most black students attend two-year community colleges."

The National Urban League president said that while a few years ago the average black family earned 62 percent of the typical white family's income, today the figure has declined to 57 percent. Black unemployment is nearly 2 1/2 times that for whites, also an increase to the detriment of blacks, he said.

Jordan said that the belief that blacks are becoming part of the middle class in "overwhelming numbers" is still another illusion. He said that a majority of black families have annual incomes lower than the government's own measure for a "lower living standard," and that less than 10 percent reach the upper living standard.

"Now what kind of progress is that?" Jordan asked the estimated 250 educators, lawyers, students and others attending the conference. "The majority of blacks are poor or near poor. The gains black people made in the 1960s were significant. But they came nowhere near closing the gap with the white citizens. And in the 1970s, those gains were eroded."

Another conference speaker, economist Andrew F. Brimmer, a former member of the Federal Reserve Board, said that the economic outlook for blacks through the mid-1980s is "only moderately bright."

"Blacks can be expected to make some further gains in narrowing the jobs and income gaps between themselves and whites," he said, "but said, "but the degree of progress will probably be rather small."

He said the U.S. "is likely to suffer from both slow economic growth (about 3 percent a year through 1982) and high rates of inflation (about 8 1/4 percent through 1982). Federal government policy will be devoted to the fight against inflation rather than to the promotion of economic growth and expansion of jobs."