The abrupt postponement of a top Soviet official's visit to China raises far-reaching questions about Moscow's policy toward Peking. The announcement caught Chinese officials by surprise, as it did diplomats and other observers here.
Ivan V. Arkhipov, Soviet first deputy premier for foreign economic relations, would have been the highest-level Soviet official to come to China since 1969. His long-planned visit, scheduled to begin May 10, was expected to include extensive talks about Soviet economic cooperation with China.
Diplomats here say the move raises several questions:
* Is Moscow warning Peking, in the wake of President Reagan's successful visit, that China's ''independent foreign policy'' has shifted too far in Washington's favor?
* Or is the Soviet Union reevaluating its whole foreign policy? Other evidence for such a reevaluation is Moscow's decision not to compete in the Los Angeles Summer Olympics.
One possible reason for postponing the Arkhipov visit could be renewed hostility on China's southern border with Vietnam, an ally of the Soviet Union. What role such events may have played in Moscow's decision is unclear.
But so far the Chinese have decided to take the announcement in stride and are withholding judgment on Moscow's immediate or long-term intentions.
According to Chinese Foreign Ministry spokesman Qi Huaiyuan, the Soviets said they ''were not fully prepared.'' However, Arkhipov's visit had been in the works for some months and was publicly announced in February this year. So far the Chinese government has refused to speculate about the Soviet decision.
''We think they have their reasons why they needed to tell us only at the last moment,'' said one top Chinese official. ''We don't feel angry, nor do we feel happy. Since they need more time to make preparations, we agree to that. . . .''
The timing of the Arkhipov trip had been widely interpreted as a counterbalance to China's warmer relations with the United States, since it was scheduled only 10 days after President Reagan left Shanghai. The proposal for a high-level Soviet official visit to China was discussed at the third round of Sino-Soviet talks last October.
According to one source, China specifically asked for Mr. Arkhipov to come. During the 1950s, Arkhipov headed the Soviet aid program in China and helped to conceive and carry out China's first five-year economic plan.
One East European said that Arkhipov was to have arrived with a ''suitcase full of projects worked out in great detail.'' These projects would have included proposals for renewed Soviet participation in Chinese industry, including steel, petrochemicals, textiles, and electric-energy generation and distribution.
There is additional speculation here that the Soviets may have postponed the visit to avoid any embarrassing comparisons with President Reagan's trip.
That visit was the climax of an active period in US-China relations. It resulted in the signing of several agreements that should significantly strengthen trade and economic ties between the two nations.
A Soviet official here told this reporter two days before Arkhipov was to arrive that there could be no comparison in the outcomes of the Reagan and Arkhipov trips to China.
Arkhipov's meetings with the Chinese, he said, would only initiate discussions about long-term projects. He pointed out that a centrally planned economy moves slowly in implementing economic cooperation agreements, and that the quick results China could expect from joint ventures with Western and Japanese private enterprises were not possible in dealing with the Soviet Union.
Communist diplomacy in East Asia has been especially active recently.
Chinese Communist Party leader Hu Yaobang was given an unusually warm welcome when he arrived in North Korea last weekend. The crowds of several hundred thousand were featured prominently on Chinese television news broadcasts earlier this week.
North Korean President Kim Il Sung is scheduled to visit Moscow later this month for the first time in 17 years.