Rapid technological development will displace millions of workers this decade. But those who have computer or related training will have the best chances for survival.

That, at least, is the thinking of some labor economists and federal officials who have been looking at the future of the American job market.

Even in fields outside the computer industry that are expected to expand, such as manufacturing and medical services, a familiarity with computers will be important, experts say.

"Computers are and will be a growth industry in this country, and there will be millions of computer jobs. But we shouldn't just focus on that. What we'll see is a large displacement of many people" as more computers and computerized robots are brought into the workplace, said Sar A. Levitan, a labor economist who is also director of the Center for Social Policy Studies at George Washington University.

The Bureau of Labor Statistics estimates that the domestic computer industry will have a yearly growth rate--the percent increase in jobs--of 4 percent to 5.1 percent in the 1980-1990 decade, compared with an annual rate of 4.7 percent in the last 10 years. There were 1.16 million computer and related jobs in 1978, but that number is expected to rise to 2.14 million by 1990, according to H. Phillip Howard and Debra E. Rothstein, economists in BLS' Division of Occupational Outlook.

Computer service technicians--the people who install, test and maintain the equipment--will experience the fastest job growth in the industry. Computer operators, already the largest group in the field, will continue to increase their numbers. But keypunch operators, whose skills have become more obsolete as new techniques for storing and transferring computer information have developed, will decline in numbers, Howard and Rothstein said in a recent study of occupational trends in the computer industry.

There were 273,000 keypunch operators in 1978. But that number is expected to fall to 230,000 by 1990, the study said.

Levitan believes the keypunch operators' fate indicates what will happen to low-skilled workers, including those with limited computer training, who are unprepared for coming changes. It is a matter of economics, he said.

"Economists keep talking about what kinds of jobs there will be and how many computer jobs there will be, but that is misleading in terms of displacement," Levitan said. He said the 1960s and 70s were periods of "cheap labor," because employers were hiring women and young people who were entering the labor market for the first time.

But the young workforce generated by the post-World War II baby boom has matured and, in most cases, is getting higher pay. Women who once accepted lower pay--on the ground that theirs' was supplementary income, for example--no longer are willing to settle for less. Labor costs, consequently, have risen in many jobs that employers now believe can be done more cheaply with computers, Levitan said.

Computerized robots are favored in assembly line and other routine tasks, such as auto painting and precision welding, where they work long hours without lunch and coffee breaks. The robots require no pay increases, no health or workmen's compensation benefits, and they don't sign union cards.

The auto industry alone has about half of the nation's 5,000 robots, and is planning to add more in its recession-driven haste to reduce labor costs.

Some industry officials say few job losses are due to automation, but to the current economic climate, where high interest rates and declining sales have moved nearly 200,000 autoworkers into unemployment lines. On that, they have some agreement from labor leaders such as United Auto Workers President Douglas A. Fraser, who has cited the economy and what he calls "unfair foreign competition" as being the chief villains behind autoworkers' layoffs.

But industry and union officials have acknowledged that much of autoworkers' job loss is permanent. And all of the domestic car makers plan substantial investments in plant modernization--"retooling"--that will automate about 20 percent of the jobs once held by humans, according to some industry estimates.

Generally, the number of computer systems is increasing from 600,000 in 1978 to an expected 1.6 million by 1983, the BLS study said. Purchase prices for many computer products are falling, a fact that makes them even more attractive to employers.

"As the cost of computer technology keeps declining, companies will continue to invest in them. The chances that companies will invest heavily in jobs that now require people are not all that good," Levitan said.

That means many jobseekers in the U.S. labor market will have to develop higher, more technically oriented skills in order to find work, said Audrey Freedman, senior research associate at The Conference Board, a New York-based think-tank for labor and economic matters.

Companies will want managers who are "more technically trained than management trained," Freedman said. Because the nation has "an oversupply of college graduates," jobs that once required a high school diploma "will require a college degree," she said.

"There will be an increased need for diagnostic thinking, versus creative thinking. There will be a need for improved mathemmatics skills, more precise language skills, the ability to understand legal communications and, of course, the ability to understand and use computers," Freedman said.

But U.S. education "in too many cases has become divorced from the world of work" and insufficient attention is given to job training in the nation's schools, she said. That means many employers--machine tool manufacturers, for example--could have as much trouble finding skilled workers as prospective employes could have finding jobs, she said.

Nearly every industry on the BLS' "faster-growing industry" list requires technically trained workers and employes who have some "computer literacy." Two of the leaders, other than the computer industry, include:

* Medical Services: nursing homes, laboratories, and other medical support functions, excluding hospitals. This industry had an annual 7.6 percent growth rate in the last decade. The projected annual growth rate from 1980 to 1990 ranges from 4.6 percent to 5.6 percent.

BLS economists attribute the decline to a "maturation process," meaning that the medical services industry gradually is reaching its saturation point in terms of employment. But the industry will continue to grow at a substantial rate because the U.S. population is getting older, using more health insurance benefits, and becoming more health conscious, the economists say.

* Health professionals: doctors and dentists. Professional health-care delivery grew at an annual rate of 5 1/2 percent in the last 10 years. The projected 1980 to 1990 annual rate is 3 percent to 3.6 percent.

Other industries in the "faster growing" category are energy related. They include coal, crude petroleum and natural gas production. Domestic energy growth is expected to continue because the United States will rely less on foreign energy production in the future, according to BLS officials.

Increased defense spending is expected to shore up sagging manufacturing industries, which have suffered greatly from declines in auto and steel production. Manufacturing firms logged a sorry 0.5 percent annual growth rate in the last decade. But defense spending is expected to help lift that rate to 2.3 percent by 1990, BLS officials say.

Still, the job-growth figures for all industries seem to support Levitan's worry about future unemployment for low-skilled and unskilled workers. Employment in all industries grew at an annual rate of 2.1 percent in the last decade. BLS economists predict that total industry employment will grow at an annual rate of 1.6 percent to 2.3 percent in the 1980s.