A federal appeals court has cleared the way for the Little Rock school system, which 25 years ago was the scene of the first major confrontation between federal and state officials over school integration, to begin classes in two weeks using a desegregation plan that will leave 1,500 black children isolated in four nearly all-black elementary schools.

On Monday, the 8th U.S. Circuit Court of Appeals in St. Louis denied an appeal to stop the plan.

The appeal was filed by black parents who said the plan would resegregate the school system. John Walker, an attorney for the group, said he would make no further appeals.

In 1957, President Eisenhower called out federal troops to escort the first black students to Central High School after Arkansas Gov. Orval Faubus defied a Supreme Court order to desegregate the schools.

Today, 20,000 students are in the Little Rock schools. About 65 percent of them are black, the reverse of the ratio 10 years ago. The elementary schools are more than 70 percent black, but high school enrollment, including Central's, is about half white.

Whites have been leaving the school system at the rate of 2 or 3 percent a year.

School board members, worried that the trend would continue, proposed a plan last fall that would have put half the city's youngest black students in segregated classes in integrated schools.

U.S. District Court Judge William Overton rejected the idea as constitutionally impermissible.

But last month he approved a plan that a new school board, made up of six whites and one black, said would reduce busing and the number of racially identifiable schools when classes start Aug. 30.

A spokesman for the system said yesterday that five schools were more than 80 percent black last year, and the number was projected to rise to seven this fall without the new plan.

Edward Kelly, the superintendent of schools in Little Rock, denied suggestions that the district was trying to retreat from an integrated system.

"That's not the intent of the board or the city," he said in a telephone interview yesterday. "We have been faced with resegregation along economic lines despite our efforts to integrate the community. We're attempting to deal with reality."

School board lawyers told the appeals court that the plan was a temporary one while the board explored a possible solution involving the neighboring Pulaski County suburban district.

Paul Masem, Little Rock schools superintendent until he was forced out in June, said by telephone yesterday that the new plan "is a Band-Aid . . . . The real answer is outside the district."

Although the appeals court told the school board it should try to start voluntary integration with neighboring districts, Masem said that when he suggested such talks, the Pulaski County board directed its officials to "sever all discussions."

The suburban district has 27,000 students, 20 percent of them black.

Kelly said the city district would try again to interest the suburban district in a broad integration plan. "History has not been in our favor," he acknowledged.

In approving the new plan, the court of appeals panel also told the Little Rock board it should consider ways to enrich the programs at the four nearly all-black schools and other means of providing students with integrated experiences.

Masem said he was convinced that the Reagan administration's decision to oppose busing in school desegregation cases had given school boards a signal to retreat from integration efforts.