Smiling, looking healthy and chain-smoking Panda brand cigarettes, Communist Party Vice Chairman Deng Xiaoping appeared on television tonight, ending his mysterious, five-week public disappearance and reaffirming his dominant role in national politics.

Deng, 77, whose prolonged absence prompted rumors that he had been shot, stricken by old age or toppled in a bloodless military coup, was shown engaged in animated talk with former Cambodian head of state Norodom Sihanouk at a meeting in the Great Hall of the People.

Deng told Sihanouk that he had been resting outside Peking for several weeks, according to the broadcast announcer. Deng brushed off speculation about his politicial well-being by declaring that China is enjoying "unprecedented political stability."

Far from protecting his own political flanks, Deng indicated that he had been spending time preparing for the upcoming bureaucratic housecleaning that will rid the ruling Communist Party of officials who are elderly, corrupt or unwilling to implement his economic reforms.

"We are determined to take it as a revolution," he told Sihanouk. "Of course, this is a revolution in administrative structure, not a revolution against anyone."

Coming 37 days after he last appeared publicly, Deng's surfacing seems intended to reassure domestic supporters and foreign diplomats who have been puzzled over the whereabouts of the only Chinese politician believed to be influential enough to maintain the nation's fragile political stability.

His cameo TV appearance with a former state leader who still is held in high regard here may have underlined Deng's continued preeminence but it does little to explain why he dropped out of sight for so long. Nor does it shed much light on what he has been doing.

Speculation began when Deng failed to appear publicly with other Chinese leaders on the Jan. 25 Chinese New Year. It intensified after Chinese officials disclosed that Deng had withdrawn from daily decision-making to focus on major policy issues.

Although Deng often speaks of his desire to elevate younger officials to leadership positions, he had been expected to remain actively involved in politics for the next few years to shore up positions of his two proteges--the party chairman, Hu Yaobang, and Premier Zhao Ziyang.

Chinese sources said Deng intentionally dropped back from the political front line to divert attention to his two disciples and to emphasize China's new rule by "collective leadership," with Hu running the party, Zhao running the government and Deng running the military.

Deng maintains his status as first among equals, but he withdrew from the public spotlight several weeks ago to "give the younger men a chance to run the country" without Deng overshadowing them, according to a party ideologist.

He said Deng is preoccupied with being succeeded by leaders cut in his mold--energetic, pragmatic modernizers--and he wants to prepare China and the rest of the world for the day when he is unable to play an active role himself.

"It is like a short trial," he said. "Deng can lay back and watch how things work. If he doesn't like what he sees, he still can make adjustments."

Two days ago, Hu emerged amid the speculation about his patron and declared that "our party exercises collective leadership." As if to say that China can function without Deng at the switches full time, he noted that "the core of party leadership is very strong."

"It seemed that Hu was saying, 'Hey, I'm in charge, the country is running smoothly and Deng Xiaoping hasn't been seen in weeks,' " said a West European diplomat.

Foreign analysts believe that Deng remains as strong as ever but has decided to take a back seat for a limited time to encourage other aged officials to step down.

The elderly are the first target of the bureaucratic trimming and rectification that is expected to cut central government jobs by a third, or 200,000 employes. The campaign also will prosecute officials found guilty of abusing their public trust.

During his five-week absence, Deng reportedly was lining up support for the campaign. He is believed to have secured pledges from top political leaders not to interfere with the housecleaning by protecting officials listed for dismissal.

In his two-hour session with Sihanouk, Deng said the streamlining already is "going on very smoothly. The comrades in our party, including the older ones, hold identical views on this issue. I think the job can be finished much earlier than expected."