With youth crime rising, Chinese authorities are encouraging an unusual debate within the once taboo social sciences to further the search for a solution.

For years, juvenile delinquency hardly was acknowledged here and was written off as a product of China's unresolved "class struggle" or past economic exploitation. Officials prided themselves on the safety of their streets while quietly exiling the few youth offenders to work camps for hard labor and Marxist teachings.

In this reform era, however, psychologists and sociologists branded as reactionaries just a few years ago are being allowed to come forth with analyses possibly painful to the Communist government here.

Looking beyond Marxist theories, they are pinning the disturbing rise in juvenile crime on complex social factors including official corruption, unemployment, poor parental upbringing, stunted educations, bad reformatories, rising expectations and the breakdown of traditional social values.

Law journals are exploring the subject for the first time, quoting liberally from western psychologists who trace juvenile delinquency to unhappy mother-child relationships or to unformed self concepts.

Specialists are opening forum discussions at universities, courts are training youth counselors and trade unions are setting up special youth centers. Sociologists are compiling China's first text on youth offenders--a 400,000-word tome--and have been exchanging hundreds of scholarly papers.

Part of the reason for the academic upsurge is the dramatic increase in crimes by persons between the ages of 14 and 25. In Shanghai, the rate of youth crime has increased from 10 percent of total offenses in 1950 to 62 percent in 1980. In many other cities, juveniles are said to account for more than 70 percent of total crimes, mostly thefts.

Even in the tradition-bound Chinese countryside, youth gangs reportedly have beaten up teachers and looted and wrecked school property.

Perhaps as significant are the changes observed in young offenders that seem to discredit old Marxist explanations for youth delinquency.

In 1950, "class enemies"--former landlords, Nationalist Party officials and security guards of old capitalists--were held responsible for most of Shanghai's thefts, according to the magazine Jurisprudence. But 30 years later, the blame was shifted to the pillars of socialist society: young workers, peasants, cadres and students.

Hard facts also deflate the theory of economic deprivation. In Changzhou, one of China's richest cities with a high rate of employment, more than 73 percent of the crimes in the first quarter of last year were committed by teen-agers, according to Peking Daily.

Three quarters of the delinquents at a reformatory of another city came from middle-class homes by Chinese standards.

In search of new theories, the specialists agree on the devastating moral effects of the Cultural Revolution from 1966 to 1976. The campaign turned social values upside down, unleashing youths to rebel against authority and tradition in the name of political purity.

"Beating, looting and smashing were regarded as heroic acts," said sociologist Fang Po, writing in the journal Legal Study. "This anarchist tendency still constitutes the major ideological root of juvenile delinquency today."

Corrupt officials have since accelerated the criminal slide of many juveniles "who have a skeptical view of party propaganda and even believe committing crime is justified" because of official abuse, said Fang.

In this moral vacuum, youths are said to be increasingly drawn to the western lifestyles exposed to them through China's tentative opening to the outside world.

"These people do their utmost to get modern consumer goods, such as color televisions, tape recorders, cameras and motorcycles," said the Legal Study article. "They will not stop at anything until they are led to crime. Some young people . . . sing vulgar songs and pass around pornographic materials. They seek unrestrained sexual freedom, and in a few cases barter away their moral integrity and national honor."

But this political malaise is considered only part of the complicated matrix of juvenile delinquency in China.

Family background is now regarded as an important factor especially among the children of broken homes or of parents who were persecuted in past political witch hunts. According to one survey, 17 of 90 inmates in an unnamed city jail were the offspring of political victims.

"When unfortunate parents are persecuted," said the survey, "their children become homeless and destitute. They become street urchins feeling isolated, melancholy and indignant. Poverty and bad influence easily turned them to crime."

Schools also have been blamed for the criminal spurt. Teachers who divide classes into slow and advanced pupils typecast the laggards as losers, eroding their self-respect, according to sociologist Fang. Other teachers are said to be too permissive, allowing their students to have love affairs, smoke cigarettes and drink liquor.

If youths escape the perils of bad family and school, they stand a good chance of becoming criminals if they do not find a job, said Fang. He cited a 1979 survey showing that four of every 10 offenders were jobless. This is said to be a troubling finding in a nation chronically short of jobs because of its huge population.

The new criminal sociologists prescribe better moral training at every level of Chinese society, but they generally conclude that reformatories now housing wayward youth are failing in their jobs.

"Some reformatories have even become institutions for teaching criminal skills," said Fang. "Occasional offenders may become hardened criminals after release."