Although suspicious of the U.S.-Soviet summit talks in Vienna, China is now pondering a change in its own hostile relations with the Soviets that could affect the future of both superpowers.

Moscow has proposed talks with the Chinese this summer on improving relations and Peking says it is "studying" the matter. Some leading Chinese seem to feel their new modernization program will gain and their border difficulties recede somewhat if the Soviet Union is rendered less uncooperative. Yet there is opposition to the talks in China and few Chinese really trust the Soviets.

Foreign analysts here, looking back at 20 years of open Sino-Soviet enmity and a recent war between China and Moscow's ally, Vietnam, tend to be skeptical of the chances for improvement in relations between the two Communist giants. Yet a slight thaw would appear to serve American interests.

"After all," said one U.S. observer, "a Sino-Soviet war would be almost as big a problem for us as it would be for them."

Peking has made no secret of its contempt for the SALT agreement being signed in Vienna. The Chinese have regularly scoffed at the notion that Soviet aggressive desires can be contained by pieces of paper.

The Kremlin bosses are past masters of tricks and machinations," the new official Chinese news agency correspondent in Washington, Peng Di, said in a story last month on the SALT negotiations.

The Soviet, ignoring such talk, have recently tossed a large bouquet of friendly signals in Peking's direction. They made tried to ease some Sino - Soviet irritants and improve chances for talks now being discussed between the two countries. Earlier this month, the Soviet Communist Party newspaper Pravda printed what some observers said was the first favorable press report on China in several years - a three-paragraph item on Chinese attempts to curb pollution.

Moscow appeared also to silence what Peking probably considered a particularly irksome ploy, a Chinese-language radio station in the Soviet far east that early this year tried to bill itself as the voice of dissident Chinese inside China.

The Soviets have tried this gentle approach before, particularly after the death of the rabidly anti-Soviet Chairman Mao Tse-tung in September 1976. Mao's uncertain, faction-ridden successors rejected the Soviet overtures, but now a pragmatic group more confident of its ability to handle the Soviets is in command, led by Vice Premier Deng Xiaoping.

Appearing soft on the Soviet Union is as great a domestic political handicap in China as it is in the United States. Yet Deng and his colleagues appear to see more merit in less belligerent relations with Moscow - just so they are not compelled to reduce drastically their usual torrent of anti-Soviet propaganda. Further increases in trade with Moscow, now up to about $516 million annually, would help their modernization plans.

China's tense southern border with Vietnam and Laos might become less of a drain on China's military budget and less distracting to a leadership wrestling with domestic troubles if the Soviets could be persuaded to rein in the Vietnamese a bit.

In early April, Moscow had surprised foreign observers by suppressing its annoyance at Peking's announcement of curtailment of a 30-year friendship pact. Instead, the Soviets picked up on what appeared to be an off-hand Chinese suggestion of talks on relations. Moscow moved to set an actual date for discussions on improving relations.

The most recent Soviet proposal, for talks to begin in Moscow in July or August, is being studied by the Chinese. Press reports from Peking say the Chinese are expected to respond positively, although without any great enthusiasm.

The Soviet initiative appears to be an experiment, an attempt to determine it some veteran Chinese officials recently returned to power want to recapture some of the good feeling of the 1950s when they were last in command.

The Soviets would like more trade with China, less Chinese pressure on Vietnam, fewer Chinese attempts to sour the Japanese on future economic cooperation with Moscow and generally less ideological sniping.

Even if the Chinese do not believe the Soviets will grant them any concessions along their joint border or stifle the Vietnamese, it appears to be in Peking's interest to go along with talks. If the Soviets entertain some hope of concessions from Peking, they may refrain for a while from acts that would otherwise provoke Chinese fears of being encircled in Southeast Asia by three hostile, Soviet-supplied powers - Vietnam, Laos and Cambodia.