Peking's protest movement reached unprecedented intensity today with wall posters praising the United States, expressing envy of Taiwan and suggesting that Chinese leader Hua Kuo-feng might have obtained his post illegally.

Diplomats in the Chinese capital contacted by telephone said Peking residents had begun to escape freely in discussion with foreigners about their desire for a more democratic China. Crowds cheered on Westerners trying to read wall posters that attacked a growing number of party leaders for resisting new, pragmatic social and economic policies.

"There hasn't been a situation like this in more than 20 years," said one Canadian diplomat, recalling a brief outpouring of public democratic sentiment in 1957 that was suppressed by Chairman Mao Tse-tung.

There is growing puzzlement over what the current leadership will do about the sudden return of dissent and debate, which could seriously distract officials charged with reviving the staggering economy.

More posters appeared directly attacking Mao, who died Sept. 9, 1976. They followed the first landmark poster criticizing the late chairman that appeared Nov. 19, opening the floodgates of a new wall poster movement.

The most striking of the new posters took up 62 pages along a fence facing the maosoleum where Mao's body lies alongside Tienanmen Square. It linked Mao's memory to superstition, which the poster said had crippled recent Chinese progress.

"America is a capitalist country and the most developed in the world," the poster said, arguing that rapid American progress was the result of casting supersitition aside.

The poster seemed a reaction in part to a remarkable series of articles on American life in recent issues of the official People's Daily. As part of China's new policy of candor in the official press, the articles painted the most glowing official Chinese portrait ever of prosperity in the United States.

Foreign residents of Peking said another poster surrounded by dozens of Chinese went so far as to admit grudging admiration for the anti-communist government of the offshore Chinese island of Taiwan, Peking's arch-enemy in a still unresolved civil war.

"Why can't the national economy catch up with that of Taiwan, controlled by the Chiang Kai-shek clique" the poster asked.

As reports persisted of high-level meetings in Peking, a particularly provocative new poster made the most direct attack to date on the current Communist Party chairman and state premier, Hua Kuo-feng.

It said a Central Committee resolution putting Hua in line to succeed Mao as party chairman and making him premier in 1976 "went against democracy and the legal system."

Hua was established as Mao's heir apparent in a Central Committee resolution passed April 7, 1976, two days after a riot in Tienanmen Square rocked the capital. The rioters had supported pragmatic policies of the late premier Chou En-lai and his portege, Vice Premier Teng Hsiao-ping. Teng was purged in a resolution accompanying the one making Hua first party vice chairman and premier.

Hua appeared to cooperate with many Teng supporters after Mao's death. He endorsed such Teng policies as resuming college entrance exams based on academic merit rather than political reliability, increasing worker bonuses and reviving active trade with the West. He agreed to restore Teng as number three in the hierarchy in July 1977.

But many Teng followers are thought to resent the fact that Hua rather than Teng remains on top. There have been occasional indications of a split between the two men.

Despite the sensitivity of these political issues, Chinese in the streets have become increasingly bold this week about airing them in front of foreigners. One Europeans diplomat said as he was reading a poster yesterday a Chinese handed him a note suggesting he would find a more interesting poster a little further down the wall. He went to the spot and saw a forthright attack on Mao.

An Eastern European stumbling over some Chinese written characters while reading a poster by flashlight yesterday evening found Chinese in the crowd quickly volunteering to help him decipher the more difficult calligraphy.

"A Chinese from one of the ministries told me late this week, without hesitation, that China will not progress until it has fuller democratic rights," one diplomat said in a telephone interview. "He said China didn't have much democracy now, but was moving toward having more rights as in Western Europe. He thought Switzerland was a good example to follow."

Reuter correspondent Christopher Pritchett reported Chinese wall poster readers talking freely with foreigners about China's troubles.

"Never have I been mobbed like this," Pritchett quoted one Chinese-speaking diplomat as saying. "It was unimaginable in language school that one would one day be surrounded by crowds in Peking discussing the merits of democracy and law."

It is still unclear how much of the new debate and dissent has been inspired by high party officials and how much is spontaneous.

The official press has encourage talk of democracy in recent weeks with a series of articles suggesting some loosening of China's authoritarian system. The People's Daily printed a letter from a soldier proposing that local government officials be freely elected. An article urging more democracy that first appeared in a youth magazine has been widely reprinted. Stories of some factories electing their managers have appeared in the official press.

Ordinary Chinese still seem to remember, however, the labor camps that were set up to receive people who criticized the Communist Party and supported democracy during the 1957 "100 flowers" liberalization campaign. An official announcement earlier this month cleared the last batch of these so-called "Rightists" of 1957. Nonetheless, few if any of the wall posters calling for democracy this week included the authors' names.

In the past, wall poster campaigns have signaled debate at the top of the Communist Party over new policies. Analysts have predicted a new meeting soon of the Central Committee to decide its attitude toward the 1976 resolutions, toward the position of Hua in the party and government and toward free public expression. The committee might also have to decide other issues such as how rapidly to expand foreign trade and whether to train a scientific elite, policies that Mao did not entirely approve of.

The outpouring of wall posters, may indicate that the leadership is unable to impose discipline on dissidents because it has not yet decided its own policy.

Diplomats said a few policemen stood near the crowds that read today's posters, although they seemed to be doing little more than reading the posters. One Peking resident said a crowd was briefly cleared away from a large poster in Tienanmen Square so police could photograph its contents. Few posters, no matter how controversial, have been torn down so far except for a few that vigorously defended Mao.

The Tienanmen poster, signed by eight men from Kweichow Province identifying themselves as the "Democratic forum," said: The new thinking, the great democratic and human rights to which we aspire, which we seek, have today raised their heads in the great land of China.

The poster attacking the two 1976 resolutions that purged Teng and promoted Hua said the decisions were not products of Marxism but the willful products of feudal, fascist dictatorship . . . They raped the people's will."

The poster referred to the National People's Congress, which is supposed to be in charge of appointments of top government of officials, even though it had no apparent part in Hua's 1976 appointment as premier and Teng's temporary loss of his vice premiership.

"No wonder foreigners call the National People's Congress a rubberstamp parliament. It has only its name but no real power," Pritchett quoted the poster as saying. "The two resolutions should be publicly canceled to defend the legal system."