China's democracy movement, after a swing through the provinces and a splash in the world press, has returned sober and sanitized to the dirty gray and yellow bus depot wall where it began.

The Chinese still call it Democracy Wall. Wallposters in bright pinks and yellows and greens cover it for 100 yards or so. Each night, however, a few men in plain clothes arrive to inspect, trim , blacken or remove those statements that go further than the Communist Party wants to go.

"Everything on the wall now has to be taken with great suspicion," said one Westerner who visited the wall daily for months and befriended one of the prominent poster authors, now in jail. "Whatever remains up has been completely checked by the government."

The wallposter, or what the Chinese literally call a "big character report," has had an odd and tumultuous history in 20th century China, but rarely anything like the rollercoaster ride it has taken these last few months. While the impact of the wallposters on the world press has been enormous, perhaps out of proportion to their reliability and the size of their following in China, the mystery shrouding who writes them and why they are written has dissipated a bit.

The old wall screening the bus-yard along the Avenue of Eternal Peace still draws several dozen readers morning and night. Occasionally some of the old fire of last November, when almost no Chinese leader was safe from wallposter attacks, come back. Now, however, such writings appear to be tolerated only as a safety value.

This weekend, wallposters scorched the Chinese leadership for failing to restore the reputation of the late Liu Shao-chi, the former Chinese president who was purged for his efforts to strengthen party control at the expense of the personal power of the late Communist Party Chairman Mao Tse-tung. A poster stayed up through late March, right after the party clampdown on criticism, even though it described China's effective leader. Deng Xiaoping, as a prospective "dictator" and "no longer worthy of the people's trust and support."

A wallposter attacked Deng and his cohorts for continuing praise of Mao Tse-tung and not emphasizing the many "mistakes" that deceased revolutionary leader made in removing good people from office. The poster stayed up for a week in late April, then was covered by a new poster promoting a complicated new system for transliterating Chinese.

This was only one of several slightly crackpot ventures that have found their way to the wall recently. There is an occasional hawker for a mathematical game, and even a panhandler. Magazine salesman, putting out the new underground journals leaning toward short stories and verse, sell their wares.

In a country with little interesting reading matter, Peking residents are still drawn to the endless personal appeals for justice against isolated bureau-cratic abuse that make up the bulk of wallposters now, "I call the state council three times a day with no results," a typical one says. They may be written on notebook size paper with ballpoint pen or on a bigger sheet with inkbrush. In other provincial Chinese cities, similar appeals can be seen, although in far fewer number than at the height of the movement.

There were never really enough literate Chinese during the imperial dynasties to support a wallposter movement, butwithin the governing elite, business was carried out through memorials to the emperors which had some of the flavor of today's posters. Usually only young men who wrote graceful essays could pass the examination for important positions as government officials.

After the last of the dynasties fell in 1911, a growing interest in democracy and a gradually expanding public education system allowed the wallposter campaign to come into its own in the 1920s. Liberal reformers, many of them young men and women who now survive as elder statesmen in Peking, plastered city walls with appeals for end to warlord repression, increased education for the masses and strong action against Japanese aggression.

Once the Communist Party won its 1949 victory, the need for protest subsided. Then Mao began to see wallposters as a way to stir peopel against officials he wanted chastised or removed. In the 100 Flowers Campaign of 1957, many answered Mao's call to criticize the party's bureuacratic excesses, and then found themselves packed off to labor camps.

During the Cultural Revolution of the late 1960s, Mao's youthful red guards honed the wallposter into a reliable political weapon.

Western China watchers became confident that a well-coordinated wallposter attack in China was a reliable signal of impending political dismissal. The poster-writers were usually carrying out orders from above.

Then, in 1973, "we all got burned with the case of Li Desheng," said one veteran China watcher, "and we learned that posters no longer meant the same as they used to." Li, the military commander of Peking and later the commander in Manchuria, "was attacked in wallposter throughout the country," the analyst recalled. "We reported him purged seven or eight times."

Yet, Gen. Li emerged relatively unscathed, and remains Manchurian commander to this day. Analysts began to see that even minority factions in the ruling Chinese Communist Party Central Committee had begun to use wallposters, to score points against their political enemies but not to remove them.

After Mao's death in 1976, as various leadership groups maneuvered to inherit his mantle, contradictory posters appeared more frequently. Finally, late last year, the veteran officials who had returned to power after being victimized by Mao sent down signals that attacks on the great revolutionary leader himself would be useful.

The resulting outpouring of criticism of all aspect of social rule apparently startled Deng and his colleagues, and they pulled back. They realized the poster writers were a few urban intellectuals. The vast countryside was not involved.

Wallposters began to be pulled down. Ren Wanding and Wei Jingsheng, young electrical technicians, who had become outspoken in favor of unlimited democracy and attracted attention in the foreign press, were arrested. Both had friends or relatives in the party, and had responded to the encouraging early signals, then refused to back off when another signal came to limit the movement.

A leading Deng lieutenant, Hu Yaobang, has reportedly told a party gathering that Wei's and Ren's actions were wrongheaded, but not criminal, giving hope for their eventual release.

A significant April 5 editorial in the People's Daily appeared to tell protesters that they could continue to use Democracy Wall, just so they did not become an organized opposition and dropped the theme of human rights, which grates on Communist ears.

This weekend, the nocturnal editors of Democracy Wall stripped away some of the attacks on the failure to rehabilitate Liu Shao-chi, but left up those that argued Liu was a good man because he really had supported Mao. A May 3 speech by Chairman Hua Guofeng even appeared to borrow a quote from an earlier wallposter: "Without people's democracy, there would be no socialism."

The compromise does not please many Westerners here, however, who had hoped that their suddenly frequent, personal contacts with the Chinese protestors could have continued. "I think it highly ironic," said one, "that my only breakthrough into Chinese society was represented by a wall." CAPTION: Picture, Earlier this year, wallposters discussed U.S. ties.