Teng Hsiao-ping, China's most controversial leader, has made an unprecedented comeback from the second political purge of his career, Peking wall posters announced tonight.

The posters, reported by foreign journalists in the Chinese capital, indicated that Teng had been returned to power as part of a ruling triumvirate including Communist Party chairman and Premier Hua Kuo-feng and Vice Chairman and Defense Minister Yeh Chien-ying.

The reinstatement of the 73-year-old outspoken advocate of modern management techniques is a strong endorsement of the renewed emphasis on foreign trade, labor discipline and material incentive that has marked the post-Mao era in China.

Teng also happens to be the most experienced of top Chinese officials in dealing with Washington, and he might be expected to resume his role as the key negotiator in China's developing relationship with the United States.

The posters, displayed on walls outside the Ministry for Economic Relations with Foreign Countries and signed by sections of that ministry, said: "Warmly welcome and support the central decision to appoint Comrade Teng Hsiao-ping to the post of party vice chairman, vice premier of the State Council, vice chairman of the military affairs commission and army chief of staff," foreign news agencies reported.

The Peking reports said there was no immediate official confirmation of the appointment, but several high officials and articles in the official media have hinted lately of Teng's return to favor. No one attempted to remove the posters, as usually happens with unauthorized announcements.

The appointment as outlined in the posters would generally return Teng to the posts he held before a group of the late Chairman Mao Tse-tung's most orthodox followers forced his purge early in 1976. His official government post then was first vice premier of the State Council, and there was no indication tonight if he would resume that exact title.

When Premier Chou En-lai died 18 months ago, Teng seemed to be Chou's likely successor and stood second only to the ailing Mao in political influence. Foreign analysts and many Chinese were caught by surprise when Hua, the little-known public security minister, was catapulted over Teng to become acting premier, then premier and finally Communist Party chairman after Mao's death Sept. 9. Although Communist sources here say Teng has sworn allegiance to Hua, it remains to be seen how Teng will get along with a party chairman far less experienced and 16 years younger than he is.

There have been several reports that the Chinese are preparing for a national party congress later this year to legitimize Hua's administration. The reported Teng reappointments would seem to be further preparation for this event.

If Teng's return is quickly confirmed, it would not be surprising to see him play the key role on the Chinese side when U.S. Secretary of State Cyrus Vance arrives in Peking for talks Aug. 22. Teng is the highest-ranking Chinese Communist leader ever to have visited the United States, and he thought to be the only Politboro member ever to have met the new American Secretary of State.

The two men saw each other when Vance, as a private citizen, led a Rockefeller Foundation delegation to China in 1975. There was a brief clash when the ever-abusive Teng made light of Vance's concern over nuclear proliferation.

After Chou fell ill in 1974, then-U.S. Secretary of State Henry Kissinger dealt with Teng and reportedly found him less agreeable as a negotiator than the suave Chou. Teng met for two hours with President Ford during Ford's visit in 1975.

Teng, a wise-cracking war hero and bureaucrat ffrom Szechwan, stands barely 5 feet 5 but has a towering reputation for getting things done. He was active in early Chinese Communist organizing in France and Russia in the 1920s, then returned to China to build a reputation as a party organizer and army political officer in the successful civil war against the nationalist government of Chiang Kai-shek.

By 1965 Teng was the party secretary general with considerable influence in both domestic and foreign affairs. But he became a leading victim of Mao's disenchantment with veteran party bureaucrats who Mao thought were trying to curtail his free-wheeling style of government.

When Mao's Cultural Revolution began in 1966, its No. 1 target was President Liu Shao-chi as the representative of those who put too much emphasis on steady economic growth and too little on the mass political campaigns Mao thought necessary to keep the revolution vigorous and the country free of ruling cliques. Teng, who had also worked closely with Liu, was labeled the "No. 2 party person taking the capitalist road" and disappeared from sight.

On Red guard indictment against Teng issued in 1967 charged that he was so addicted to bridge that he and his cronies stole state building materials for the construction of a card-playing club in Peking. He was charged with even commandeering government aircraft to fly his bridge-playing friends out on provincial tours with him.

As the Cultural Revolution cooled off, Chou began to bring back purged bureaucrats who were needed to put the government administration back in shape. He particularly appreciated Teng's talents, and within two years of his reappearance in early 1973 Teng was holding a slate of posts in th party, government and army giving him more influence than he had ever had before.

This obviously distrubed those members of the Politburo who had profited from Teng's purge during the Cultural Revolution. Four of them - including Mao's wife, Chiang Ching, and three Shang hai administrators - apparently persuaded Mao in early 1976 that Teng was rewriting Maoism to suit his own more pragmatic policies.

Teng was shunted aside in favor of Hua. In April 1976 Teng was blamed for a violent demonstration in central Peking indicating sympathy for Teng's policies, including long-overdue wage increases. He was promptly dismissed from all his leadership posts.

In a fierce struggle over the succession after Mao died, Hua turned on the Chiang Ching faction and, with army help, had them arrested and removed from power.

Many of Hua's supporters in that lightining purge of early October were veteran party men and old colleagues of Teng. The vehement mass campaign to criticize Teng personally and his pragmatic policies soon ended, and by November hints of his second rehabilitation began to appear.

Teng's return to grace did not appear to go completely smoothly. Some Chinese officials appeared to be bothered by overturning a decision that had Mao's sanction, and many people obviusly feared that Teng would use his renewed influence to purse those who had been against him. The removal in the last few weeks of some provincial leaders who participated actively in the anti-Teng campaign last year suggested that this may already be happening.

Teng himself, who appearently spent part of his second forced retirement enjoying the hot springs at the famous South China resort, reportedly took a relaxed attitude toward his rehabilitation. He was seen at one Peking restaurant jesting to patrons to keep up the campaign against Teng Hsiao-ping. But the Chinese bureaucracy was overwhelmingly in favor of bringing him back to work, and his reported vow of loyalty to Hua sealed the bargain.

One independent Hong Kong newspaper, quoting a source who claimed to have seen internal Chinese documents, said Teng personally congratulate Hua on his purge of the Chiang Ching group.

"Even a capitalist roader like me welcomes it," Teng reportedly said.