A Chicago professor studying national desegregation trends recommended yesterday that the predominantly black Washington public schools exchange students with suburban schools to help integrate what he called "the most segregated" big-city school system in the country.

The professor, Gary Orfield, who teaches political science at the University of Chicago, said his proposal for the Washington schools is based on a report analyzing desegregation efforts between 1968 and 1980, which he has just completed for the Joint Center for Political Studies, a public policy group concerned with minority matters. The center commissioned the report at the request of the House Subcommittee on Civil and Constitutional Rights.

The report concluded that since Washington's schools are 94 percent black and the system's white population has grown little over the last decade, "significant desegregation within the system is impossible."

But Orfield recommended that Congress encourage a greater desegregation effort in Washington and other predominantly black school systems by funding programs that would allow city students to attend suburban schools without paying tuition and would develop specialized schools in the city to attract suburban students.

D.C. Schools Superintendent Floretta D. McKenzie said yesterday that she believes the kind of exchange Orfield is suggesting "would make the children of this city less isolated and let the children of the suburbs know that cities are exciting, wonderful places."

But Nathaniel Bush, school board vice president, said integration is not a primary concern for the board. "Attracting white students should not be our principal objective," Bush said. "Our responsibility is to provide the best education we can for the students we have." He said, however, that he would support exchanges "based on programmatic opportunities, say if Arlington had a program that we didn't offer in the District."

Steven Diner, an urban studies professor at the University of the District of Columbia who recently completed a history of the D.C. schools, said that in the mid-1960s, school officials here virtually gave up on achieving any sort of integration and began concentrating on "what it would take to make this black school system effective." He said yesterday that he found Orfield's proposal "not a bad idea," but unnecessary.

Orfield's report found that 83 percent of the city's students are in schools where the white enrollment is 1 percent or less, and that the only cities that come close to this level of segregation are Chicago, Newark and Atlanta.

Orfield, a former research associate at the Brookings Institution, recommended that the city use its specialized programs, such as the Duke Ellington School of the Arts and the accelerated math-science program at Ballou High School, as "magnet schools" to attract suburban students.

McKenzie said the D.C. schools already have worked with area school systems on joint miniprograms such as the recent Urban Journalism Workshop in which students from the District, Montgomery and Prince George's counties created a magazine together.

Charles Nunley, Arlington County Schools superintendent, said yesterday the idea of exchanging students is "not too far-fetched." and cited a recent program in which Arlington's Yorktown High School students attended class at the Ellington School of the Arts.

But Fairfax County schools superintendent William Burkholder called Orfield's recommendation "a rather radical suggestion" and declined further comment until he reads Orfield's entire study. School superintendents in Prince George's and Montgomery counties also declined comment until they read the report.

Orfield's conclusions yesterday were contained in the second of a two-part report that generally found that desegregation efforts are most successful in the South, thanks to court-ordered busing, and that the most improvement is now needed in the Northeast and Midwest, especially in large cities.

School segregation ended in the District of Columbia as a result of a 1954 Supreme Court decision, Bolling v. Sharpe, decided on the same day as the Brown v. Board of Education case that outlawed dual racial school systems nationwide.

In D.C. classrooms, however, blacks and whites continued to learn apart as a result of a rigid tracking system that separated students by ability until 1967, when Julius Hobson succeeded in getting the court to agree that the D.C. tracking system discriminated against black students.