Secretary of State Cyrus R. Vance yesterday unveiled a comprehensive proposal designed to increase the power of senior State Department officials to cull ineffective Foreign Service officers, reward those who perform well, and promote younger officers faster.

Citing increased dangers and complexities in service abroad, Vance told a congressional panel the proposal is a long-needed overhaul of the "obsolete, cumbersome . . . personnel system [established in 1946] which now supplies three-fourths of our ambassadors."

Parts of the complex 204-page bill are expected to draw opposition from various factions in the Foreign Service. That, plus congressional disinterest or lack of knowledge about the Foreign Service probably will delay final action at least until late this year, according to congressional aides.

The proposal would affect almost 12,000 Foreign Service employes worldwide, including several thousand in the Washington area in the Department of State, Agency for International Development, International Communications Agency and other organizations.

The American Foreign Service Association, which represents around 10,000 of those employes, opposed earlier versions of the proposal but its leadership is trying to moderate that attitude among members because of concessions won in recent meetings with Vance and other officials, according to AFSA President Lars Hydle.

Continuing a trend toward stronger management of the work force, the proposal parallels President Carter's major revision of the Civil Service System enacted last year.

Vance, calling the legislation a major goal for his final 18 months in office, outlined the elements of the plan at a joint hearing of subcommittees of the House Foreign Affairs and Post Office and Civil Service committees. They include:

Linkage of tenure, promotions and incentive pay to quality of performance.

Creation of a new Senior Foreign Service, similar to the Civil Service System's Senior Executive Service. It would allow the top three ranks to trade job security for a chance at higher pay for outstanding performance.

Officers could request to join the new senior service, but if after joining they were not promoted within a certain time they would be considered "passed over," and, as one official put it, could make a "timely decision" about a second career outside the Foreign Service.

For many years, most senior officers have not been subject to dismissal for poor performance, the State Department's undersecretary for management, Benjamin H. Read, told the panel. This meant the service had to rely heavily on retirement at age 60 make room for others.

The new proposal does not affect retirement provisions.

Lowered promotion rates have had "a crippling effect on morale, and some excellent and most promising younger persons were lost to the service as a result," Read said.

Other provisions include:

Clear division of the Foreign Service, whose members are willing and obligated to serve overseas, from Civil Service-type employes who do not intend to serve overseas. Approximately 1,500 Foreign Service employes in the latter category would be converted, without loss of pay or benefits, to Civil Service status.

Establishment of a stronger, statutory basis for employe management relations and a new Foreign Service Labor Relations Board and Impasse Disputes Panel. This was the most important concession won by the AFSA, Hydle said.

Strengthened commitment to "mitigating the special hardships and strains on Foreign Service families, and advancing equal employment opportunity" in the service.

Vance responded yesterday to charges by some members of Congress, led by Rep. Patricia Schroeder (D-Colo.), that "old Boy Network" elitism persists in the State Department at the expense of women, blacks and Hispanics.

He acknowledged past abuses but added that he has initiated programs to correct the situation. "I am not satisfied with the progress yet," he said, "but we are on the right track."