About 45 percent of those who lost jobs last year when President Reagan and Congress killed the Labor Department's large public sector employment program found new positions elsewhere in the economy in the months immediately following, according to a General Accounting Office study of seven representative cities.

But the study also found that of those who got jobs, only half had full-time permanent positions. The rest were part-time or temporary.

The wipeout of the public sector employment program was one of the largest budget cuts Reagan made last year. The program provided jobs, mostly in state and city governments, for more than 300,000 people, supposedly the low-income hard-to-employ.

An eighth city was also studied and had more favorable results, but the GAO found that for special reasons, these were unrepresentative and would distort the findings if averaged in.

Assistant Secretary of Labor Albert Angrisani, who ran a special placement campaign to find new positions for those losing the jobs, said the GAO's 45 percent figure was actually higher than the placement rate normally found in past years for similar groups, and showed that the placement campaign was successful.

He said that in the past, only about 30 percent of those leaving public service jobs obtained nonsubsidized public or private work in the first three months afterward. He said the Labor Department's own survey would show more favorable results based on nationwide figures than the GAO sampling.

The GAO completed a draft copy of its report as the Senate and House Labor committees began considering whether to extend the expiring Comprehensive Employment and Training Act (CETA), of which the public service jobs program had been a part, or to create a smaller $1.8 billion job-training program proposed by Reagan.

In its report the GAO, responding to a congressional request, took a look at what happened to some of the 306,000 persons who were in federally subsidized public service jobs early in March, 1981, when the president asked for abolition of the program, then lost the jobs by July 31 after Congress complied.

The public service jobs program has been a favorite of many Democrats as a way of countering the impact of high unemployment on people with few skills or immediate opportunities to find normal jobs. But it has often been criticized, particularly by conservatives, for providing "make-work" jobs.

The president requested abolition of the program in part to save money--$3 billion last fiscal year--and in part on grounds the program was misdirected, in that the government ought to be training people, not employing them.

The GAO report indicated that, in fact, considerable efforts were made by the Labor Department, working with public employment agencies, local government units and private business groups, to find new, nonsubsidized jobs for those losing public service slots.

But through the end of October, when all those studied had had at least three months (and some longer) to find new jobs after leaving public service employment, the GAO survey of seven cities (Atlanta, Cleveland, Boston, Stockton, Birmingham, San Francisco and Providence) showed the following:

44.9 percent of the former participants were employed, another 5.5 percent were in school or other training programs and 49.6 percent were unemployed. The GAO said more than three-quarters of the unemployed made two or more attempts to find work each week.

Only 55.2 percent of those employed had obtained full-time permanent jobs. The rest held part-time or temporary positions.

Based on a relatively small sample of those employed, the GAO concluded that about three-fifths were earning more than their previous public service jobs wage, 25 percent were earning less, and the rest about the same.

The GAO found that the overall figures would look more favorable--a 58.8 percent employment rate instead of 44.9 percent--if the numbers for an eighth city that was studied, Detroit, were included.

But it said that the Detroit experience was unrepresentative and would give a "distorted picture of the average placement results" because the local agency that had run the Detroit public service jobs program had simply rehired 70 percent of the laid-off workers with its own money, a development unlikely to be duplicated elsewhere.