Civil Service Commission Chairman Alan K. Campbell called yesterday for curtailment of the hiring preference the federal jobs but constitue only 22 per cent of the national work force.

Campbell outlined his controversial proposal, which would require congressional approval, before the national convention of the American Legion in Denver.

Campbell's remarks were politely received by the Legionnaires. But Louis Clark, assistant director of the National Economic Commission of the Legion, said the group has a standing resolution "that we oppose any effort to weaken or destroy the veterans preference act as it now is." Clark said "naturally we're opposed" to legislation by Congress.

The present system of preferential hiring, Campbell told the assembled veterans, "has effectively diluted the benefits" for non-veterans who need help in getting jobs.

The practice of giving an edge to job-seeking veterans began in 1944 with passage of the Veterans' Preference Act. The law's intent was to compensate for time lost in wartime service by making it easier for them to find jobs with the government.

Now, however, the law gives veterans preference long after their service has ended and provides what amounts to unlimited tenure once they have a civil service job, according to Campbell.

The system is "curiouser and curiouser," he said, in that it has left male veterans holding a concentration of middle and upper-income government jobs while women are concentrated in lower-paying jobs.

Under present law, veterans who served in either world war, in Korea between April 28, 1952, and July 1, 1955, or who served more than 180 consecutive days on active service from January, 1955, through Oct. 14, 1976, are eligible for a five-point "adjustment" in their competitive civil exam scores.

Disabled veterans and their spouses and mothers, as well as the spouses and mothers of deceased veterans, are eligible for a 10-point adjustment.

In addition, Campbell pointed out, after test scores are computed and employers begin selecting from the "eligibles," a veteran may not be passed over, all other things being equal, unless the Civil Service Commission had granted the employing agency a waiver to do so.

In 1975, Campbell said, veterans made up only 20 per cent of the "elrgibles" but accounted for 34 per cent of those selected for jobs.

Women, on the other hand, made up 41 per cent of the "eligibles" buy only 27 per cent of those selected for jobs.

Campbell is co-chairman of the Federal Management Personnel Project, the part of President Carter's government reorganization planning that aims at streamlining employment practices. The proposals he outlined to carter are the work of that group.

Briefly, the proposals are these:

Veterans who receive a five-point adjustment on their civil service test scores should be "in some way limited either in the length of their use of preference or in their ability to monopolize the 'rule-of-three'" whereby employers must pick veterans over better qualified applicants.

No preference benefits should be extended to potential "double dippers' - those who make a career of military service, then retire, collect their pensions and apply for federal civilian jobs.

Veteran preference during a personnel reduction should eb limited. (Under present law, when a government office cuts back on personnel, veterans cannot be released while non-veterans remain on the job.:

Veterans who receive a 10-point adjustment in exam scores "should either compete as equals. Once the 10-point advantage is given, or could be hired under a special appointing authority . . . designed to deal with their specific needs."