Faced with serious un-employment and overstaffed factories, the Chinese government has begun major changes in the way it deals with its mushrooming number of elderly workers and their children.

Peking has announced a sharp increase in the size of pensions for city workers and guaranteed jobs for retired workers' children. The changes, apparently designed to move older people out of the work force as fast as possible, have resulted in 50,000 retirements in Peking this year, a record for recent years.

The changes appear, however, to aggravate unwittingly one of China's greatest social irritants and political dilemmas, the prosperity gap between city and countryside.

Despite recent progress in cutting the birth rate, China continues to be haunted by its baby boom from the 1950s and 1960s. The boom has resulted in an estimated 10 million to 20 million jobless young people in teh cities, a source of crime and great social discontent. Chinese say the new rules allowing a son or daughter to take place of each retired worker has been enormously popular, for it has allowed parents to bring children back from hard labor assignments in the countryside.

But the new rules, once applied by just a few factories, reportedly also have created tensions in some families.

"I've had Chinese tell me of real resentment from sons or daughters who lose out when a brother or sister is picked by their parents instead of them to take over the factory job," one longtime resident here said.

Chinese youth want very much to be hired by urban factories or offices because such jobs mean a guaranteed montly income - what the Chinese call the "iron rice bowl." They also provide regular grain rations, access for their children to superior city schools and guaranteed retirement benefits.

The retirement benefits were made even more attractive by an order from the State Council late last year, which now is being revealed by Chinese in conversation and in the official media.

"A pension may range from 60 to 90 percent of a worker's monthly pay," the official New China News Agency said. "This represents a 20 percent increase."

Until last year, urban workers in Peking and Shanghai who were asked about pensions usually put them at about 70 percent of their salary at retirement. Most Peking retirees this year received at least 75 percent, the agency said. This would appear to represent a substantial drain on government revenue, since expanding industry and a sharp decline in the death rate has greatly increased the numbers of retired workers.

The increase also appears to aggravate the already serious gap in living standards between countryside and city and would seem to add to he despair of city youths consigned to country jobs - one of China's major morale problems.

One official Chinese report said the pension for retired farm workers in "one of the richest" communes in the Peking area was $16 a month, about half of what many retired urban workers in Peking say they receive.

The official report candidly added: "No information is available at the present time on how many of China's 50,000 communes now offer old-age pensions. It is believed that as yet they are paid in relatively prosperous areas or farming units."

The Peking authorities, as part of the new retirement policy, have taken the unprecedented step of offering bonuses to retirees who agree to leave the city.

"Those who agree to move out of Peking [apparently to other cities] receives $95.50 and those who are willing to settle in rural area $191," the official Chinese news agency said.

Retirement age for city workers is 60 for men and 50 for women, the gency said. Women office workers and teachers retire at 55. Foreign visitors to urban factories or schools, however, often find many workers and teachers older than this and still on the job.

Although Chinese families offer elderly members far more responsibilties, particularly in caring for grand-children, some older workers appear to prefer to keep working if they can persuade supervisors to let them.

High-ranking Communist Party officials rarely retire unless forced out, for retirement brings loss of special privileges such as access to an automobile and driver and it forces officials to leave behind a great deal of personal influence and self-satisfaction.

The new retirement benefits, and publicity given them, seem designed to overcome this resitance to retirement. People who have made "outsatanding contributions" now can claim pensions of 10 to 15 percent above the norm, under the new rules.