President Bush has signed legislation designed to turn vocational education programs, long seen as dumping grounds where low achievers are taught outdated trades, into academically sound courses that prepare graduates to enter high-tech training or the work place.

The five-year reauthorization prods school districts to integrate academic skills into vocational classes and establishes funding for "tech-prep" programs that would link high schools with community colleges and would lead to associate degrees or two-year certificates.

Sen. Edward M. Kennedy (D-Mass.), chairman of the Senate Labor and Human Resources Committee, said the new law contains the most important changes in vocational programs since 1963. "Vocational programs are finally receiving the priority they deserve in the effort to rebuild our economy and make our work force more competitive," he said.

Bush and Education Secretary Lauro F. Cavazos emphasized a provision that requires states to develop, within two years, standards for judging the competency of vocational students in basic and more advanced skills.

"As a result, our educational system will be better able to respond to the urgent demand for educated workers prepared for productive careers in new, emerging technologies," Cavazos said. "This effort is critical to the vitality of our nation's economy and competitiveness in world markets for the 1990s and beyond."

The legislation authorizes $1.6 billion for fiscal year 1991, but appropriations are expected to be close to the current level of $938 million.

About 20 percent of public high school students are enrolled in vocational programs, for which the federal government provides less than 10 percent of the funding. But federal grant requirements for education programs can have a broad impact on their design at the state and local levels.

Other changes may promote a more efficient use of funding and relieve what some school officials have called an administrative headache. The old formula set aside about 60 percent of the funds for disadvantaged, handicapped, bilingual and other categories of students. School administrators complained that the categorical grants could be too small to meet any practical need.

"They were such restrictive set-asides that many states found they couldn't spend the money on the categories that were required," said Betsy Brand, assistant secretary for vocational and adult education.

The new law eliminates most of the set-asides, replacing them primarily with the funding formula used for Chapter 1, the remedial program for disadvantaged students. Minimum grants are set at $15,000 for secondary schools and $50,000 for community colleges.

In a message issued when he signed the law this week, Bush raised a constitutional objection to a remaining set-aside for "sex equity programs," which he described as being for females aged 14 to 25. "Such activities would, on their face, discriminate on the basis of gender," he said.

A White House spokesman, Stephen Hart, said that the Bush administration would inform states and districts of its constitutional objections to certain unspecified sex equity programs and its lack of objection to others.