President Reagan gave an unintentional pat on the back to court-ordered school busing when he singled out an Austin high school for praise during his Tuesday night news conference.

Responding to a question about the role of the federal government in American education, the president reiterated his position that U.S. schools began to decline in quality as the federal role in education increased.

Then, citing three inner-city high schools recently cited for excellence, Reagan added, "Just by changes from the principal's office down . . . , these schools have become what schools are supposed to be, to the extent that students are leaving private schools to transfer to these public schools."

One of the schools to which Reagan was referring is Albert Sidney Johnston High School in Austin. There is no dispute that Principal Adan Salgado played a leading role in turning around his school's record.

But Salgado had plenty of help and money, and says that the catalyst for improvement was court-ordered busing. Reagan vigorously opposes court-ordered busing to achieve racial desegregation.

"It would have been most difficult, if not impossible, to get to where we got to now without court-mandated desegregation," Salgado told Washington Post special correspondent Anna Bennett. "It may have been my doing, but it was his money," he added, referring to federal funds.

"We're pleased with the president's citing Austin as progress, but it is an insufficient approach to the massive education problems that exist in this country," said John Ellis, Austin superintendent of schools.

Before busing, Johnston had the worst image of any high school in the city, and its enrollment, 99 percent minority, was declining. School busing, which began in 1980-81, brought about 700 white students to the school. The school district poured more than $1 million in extra money into the school to make it more attractive to white parents, adding facilities, an honors program and new courses.

The school's enrollment today is 50 percent white. Test scores for minority students have improved, and those for white children have held steady. The Ford Foundation recently cited the school for excellence.