The Navy was accused yesterday of practicing "blatant" and "illegal" racial discrimination because of its entrance standards for volunteers.

Rep. Don Edwards (D-Calif.), chairman of the House constitutional rights subcommittee, Rep. Ronald V. Dellums (D.Calif.) and the American Civil Liberties Union based their accusation on the Navy's requirement that at least 75 percent of the males in any racial category who are accepted into the service must either have a high school degree or score high enough on the various aptitude tests to qualify for technical schools.

That is, 75 whites must score high enough on the entrance test before 25 whites with low scores can get into the Navy. The same percentages are imposed on blacks and other minorities.

This quota system, critics contended at a press conference yesterday, is unfair to minorities because they score proportionally lower than do whites because of inferior schooling and other disadvantages.

This is "very definitely a quota system" that "discriminates against minorities" and is unconstitutional and "illegal," Edwards said. He promised subcommittee hearings on the issue.

"Blacks and other minorities are being skillfully steered away from the military" through such quota systems, Dellums charged. He called the discrimination "blatant" and said that he wrote Navy Secretary W. Graham Clayton May 10 for an explanation but has not received a reply.

William Olds, director of the Connecticut Civil Liberties Union, charged that the quota system is resulting in blacks being rejected "even when their test scores are higher than whites" who are being accepted in the Navy.

John Shattuck, director of ACLU's Washington office, termed it incredible that the Navy was turning away volunteers who meet the minimum standards for entry at the same time the military cannot recruit all the people it needs.

The Navy issued a statement yesterday declaring that today's complicated ships impose an especially heavy demand for technically skilled people.

In a reference to racial turmoil that erupted on such ships as the aircraft carrier Kitty Hawk in the Vietnam era a Navy spokesman said that "the Navy learned a lesson in the early 1970s" - that recruiting without ensuring that the sailors accepted could advance in the Navy resulted in a disproportionate number of blacks being assigned to menial jobs.

"It is not equal opportunity to concentrate one racial group" in menial tasks, the Navy said in a statement yesterday. The service must provide "an equal opportunity for upward mobility" by sending the same proportion of majority and minority sailors to technical schools.

Tht Navy said its proportion of black enlisted persons has increased from 10.8 percent in 1974 to 12.6 percent in 1978 and will rise to 14 percent by the end of this year.