The D.C. school system yesterday released the finished version of its plan for a new "college preparatory high school" that would be open next September to students in the upper 15 percent of their classes last year. The school board must approve the concept before the school can open.

The proposed school -- which Superintendent Vincent E. Reed says should "reverse the drift toward mediocrity" in high schools here -- would operate at Hine Junior High School in Southeast, near Capitol Hill. Hine students would be transferred to other junior high schools in the area.

The controversial plan, which has been labeled "elitist" by some school board members, would require students to take more math and social science courses than other students in the system. In addition, one year of Latin and two years of another foreign language would be required.

The students also would be required to do community work in each of their four years of high school.

One of the most significant differences between the proposed school and other city high schools would be in electives offered, said Cecile Middleton, an executive assistant in the school administration. Students at the new school would be allowed to take only six electives, and they would be either advanced placement courses in English, math and science or courses a student is likely to encounter in college, such as economics and anthropology.

The District now requires the least number of courses to qualify for graduation from high school of any jurisdiction in the area. But the school board is considering a plan to require two years each of mathematics, science and social science. In addition, D.C. would become the first area jurisdiction to require at least one year of a foreign language.

Middleton said the teachers for the new school would come from within the school system, but would be screened carefully to ensure their competency in subject areas. The teachers must have five years of experience as teachers in their subject field and tenure in the public school system. Special consideration would be given to teachers with a master's degree.

Students would be admitted on the basis of their grades and standardized test scores in reading and math. They would need recommendations from an English teacher, vouching for their verbal and writing skills, a second teacher, and a civic or service organization.

A personal interview would also be required for admission.

If the plan is approved by the school board, youngsters who will be ninth and tenth grade students would be admitted to the school next September. The school would be in full operation in grades nine through 12 by September, 1982.

School officials proposed a similar college preparatory school four years ago.

But the plan was criticized both by parents in the wealthier school districts of upper Northwest, who felt it would drain their community high schools of its best students, as well as parents from the poorer neighborhoods of Southeast, who felt their youngsters would be left out of the plan.