Some diplomats here have traded in their striped pants for combat fatigues.

National conflicts that are muted by protocol in other world capitals flare into petty bickering and backbiting in Peking. The diplomatic corps is a stew of geopolitical intrigue, with the Chinese snubbing the Vietnamese, the Vietnamese blacklisting the Americans, the U.S. ambassador boycotting the Soviet Embassy, the Russians slighting the Cambodians, the Cuban envoy offending the Chinese and nearly everyone shunning the North Koreans.

An innocent cocktail party at a neutral embassy can turn into a war of insults. As a European diplomat quipped, "It's like jumping into a gilded snake pit."

Peking always has been a bare-knuckles diplomatic post. Africans have been known to accuse their foes of casting voodoo spells. In the 1970s, the fastest way to empty a roomful of diplomats was to invite the ambassador from Albania.

But embassy life really began getting sticky last fall when, by a twist of fate, ambassadors from two of the most isolated and doctrinaire missions here became leaders of the diplomatic corps.

Vietnamese Ambassador Nguyen Trong Vinh, 67, a former army general apparently accustomed to pitched battles, became the corps' dean.

The deputy deanship passed to Cuban Ambassador Ladislao Gonzalez Carbijal, a writer and physician in his seventies who is said to be a close friend of Fidel Castro.

Thus, two obscure, lonely figures suddenly were cast--strictly on the basis of their tenure here--into a pivotal diplomatic role: representing Peking's motley collection of 100 ambassadors.

The role is largely ceremonial but important in the ritualized court life here. The diplomatic doyens are supposed to be ecumenical, open men who can represent their colleagues at state dinners, speak on their behalf and organize social affairs to break the tedium of this spartan communist capital.

There also is the safety valve function so important in a hardship post: the dean is responsible for conveying to the host government the steady stream of complaints that diplomats pile up against the inadequate housing, high prices and poor services all common to Peking.

Rather than putting aside politics for protocol, however, the new leaders have caused a stir by acting out the considerable bilateral problems of their two governments.

Vinh admits he still is smarting from the U.S. war in Vietnam, and he metes out revenge these days by blackballing U.S. Ambassador Arthur Hummel Jr. from the parties he organizes for departing diplomats.

Hummel has asked to be invited, but Vinh gives him the cold shoulder. He even rejects Hummel's donations for farewell gifts, returning the money in unopened envelopes. "I just have to send my donations directly to the ambassador who is leaving," Hummel said.

Vinh never calls together his colleagues for meetings and refuses to serve as a channel for their grievances.

A Latin American diplomat whose government has no relations with Hanoi said he asked the dean to submit a protest over the high housing costs in Peking, but the Vietnamese "refused to listen to me. He walked away."

"I must be Vietnamese ambassador first, then dean," Vinh said bluntly.

Gonzalez is known as a solitary, brooding man who paces cocktail parties without stopping to chat and who rebuffs the extended hand of Latin colleagues whose governments do not recognize Havana.

In front of groups, however, he is famous for interminable paeans to departing envoys. At one recent farewell party, Gonzalez droned on for almost an hour, stopping briefly to say, "To make a long story short . . ."

Someone from his audience piped up, "Too late."

The relationship between Peking's new diplomatic deans and their host government is no laughing matter, however.

Although Peking has adopted the practice of letting "barbarians control barbarians" since the first foreign missions settled here, it broke with tradition by using its influence to delay the rise of envoys from Vietnam and Cuba, two Soviet Bloc nations it counts among its bitterest foes.

The unusual ploy began in 1979 when the Lebanese ambassador, who was dean at the time, gave notice of his plans to leave China.

Peking, then involved in a border war with Vietnam and anxious to keep the deanship from Vinh--who was the second most tenured diplomat--convinced Beirut to let its ambassador stay.

The popular Lebanese finally went home in June 1981, but Peking implored his government not to withdraw him formally.

Beirut again complied, leaving open the post for 15 months until the ambassador retired last September.

Since taking charge of the diplomatic corps, Vinh is said to be setting new records for undiplomatic behavior.

He avoids the special banquets and trips arranged by the Chinese Foreign Ministry, admittedly so he will not have to offer thanks on behalf of his colleagues.

He never consults the ministry in his capacity as dean, and is said to restrict his official Chinese contacts to the volley of diplomatic protests the two sides exchange in their still smoldering border dispute.

"I don't pay any attention to the Chinese," Vinh said in an interview. "Relations between China and Vietnam are very bad now. I don't care what the Chinese think."

Peking, in turn, does little to hide its contempt for the dean. He is not invited to sit with Chinese officials at national day receptions. Nor is he called upon as representative of the diplomatic corps to welcome visiting heads of state.

Gonzalez fares little better as the ardent Russophile whose government offends Peking for its furthering of Soviet aggression.

Fellow diplomats here recall in horror how Gonzalez so insulted his Chinese hosts at a banquet in October 1981 by giving vent to pro-Soviet sentiments that the Chinese interpreter was prevailed upon to leave great gaps in his translation.