The Rev. Joseph Lowery, president of the Southern Christian Leadership Conference, joined other local and national black leaders yesterday in announcing details of plans for an Aug. 27 march here to mark the 20th anniversary of Martin Luther King Jr.'s pivotal march on Washington.

The organizations putting together the march "still have a dream," Lowery said.

Lowery and the others--including King's widow, Coretta Scott King--said they hope the march will lead to legislation to revamp civil rights laws, establish a comprehensive job training program and call for a nuclear arms freeze.

The march is being held in commemoration of the Aug. 28, 1963, "March on Washington" led by King and a coalition of civil rights leaders. About 250,000 people attended that march, which culminated in King's "I have a dream" speech on the steps of the Lincoln Memorial, considered a turning point in the civil rights movement.

This year's event is called a "march for jobs, peace and freedom," and organizers said they hope to attract broad support among religious, civil rights, women's rights, Indian, labor, environmentalist, peace and student groups.

About 600 organizations have pledged their support for the march, organizers said. A keynote speaker has not yet been picked for the event, they said.

"This march will bring together a new 'Coalition of Conscience,' " Lowery said at a District Building press conference. "Various groups are beginning to see that we're all fighting the same enemy and that those who oppose voting rights also oppose women's rights and those who support the arms race support the destruction of affirmative action."

"Before the first march on Washington, Dr. King said that the Negro had been given a bad check. . . . Our check of freedom continues to bounce at the bank of justice," said Mrs. King.

Others at the news conference included Mayor Marion Barry; D.C. Del. Walter E. Fauntroy, who was one of King's aides; the Rev. Ernest Gibson, director of the Council of Churches of Greater Washington, who is also the D.C. coordinator for the march; and Dr. Charles Butler, president of the Progressive National Baptist Convention.

Fauntroy said that most of the marchers will come from large cities and that a "freedom train" would bring marchers from Texas, Louisiana, Alabama and other Southern states.