Expectations remain low that the latest round of talks between Peking and Moscow will bring any fundamental improvement in Chinese-Soviet relations. The talks, beginning today, are the fifth in a series of formal consultations begun two years ago which have shown little progress in resolving political and ideological differences dividing the two communist neighbors.
China's senior leader Deng Xiaoping repeated last week that three obstacles to the normalization of relations with the Soviet Union must be removed. They are: the presence of Soviet troops in Mongolia and on the Chinese border, the Soviet occupation of Afghanistan, and Soviet support for Vietnam's occupation of Kampuchea (Cambodia).
The lack of progress on the political front, however, has not obstructed incremental improvements in other areas.
''Before the fundamental issues between China and the Soviet Union are solved ,'' Mr. Deng said to a group of Japanese visitors one week ago, ''they can strengthen their contacts and exchanges in other fields.... Both the Soviet Union and China have such a desire.''
The signs of such improvement are modest: a steady rise in trade volume, an increase in academic contacts and student exchanges, and favorable reports on each other's domestic developments. Moscow also sent Peking a congratulatory note on the occasion of China's National Day on Oct. 1 - a note that included the statement, ''In the sphere of Sino-Soviet relations, our country invariably favors their improvement.''
But the mood in state-to-state relations between the two giant nations has been quite variable since the last round of formal consultations were held in Moscow last March. Moscow's abrupt ''postponement'' of the long-anticipated visit by Soviet First Deputy Premier Ivan V. Arkhipov only a day before he was to have arrived in early May was widely interpreted as a serious setback for the Chinese. Peking made no official comment on the decision and only repeated Moscow's explanation that more time was needed for preparation for the visit. Ever since, Chinese officials have affirmed that the invitation still stands.
Moscow's decision, coming only a week after President Reagan's highly successful visit to China, was followed by hostile comments in the Soviet press about the new closeness in US-China relations. The change in plans for the Arkhipov trip was also related to renewed hostilities on the border between China and Soviet-backed Vietnam.
By midsummer the mood in Peking about Soviet relations was deeply pessimistic. Soon after Deputy Foreign Minister Qian Qichen returned from Moscow in July, reporting no progress in his talks, the Peking Review published a blunt appraisal of Chinese-Soviet relations.
''The real problem lies in the fact that while the Soviets attempt to control us, we are opposed to being controlled. Or, in the Kremlin's logic, you are good and revolutionary if you toe its line, and you become a bad counterrevolutionary or a narrow-minded nationalist if you don't,'' wrote a leading Chinese specialist in Soviet affairs, Wang Jinqing.
A more conciliatory mood has emerged since early September when the Soviet and Chinese foreign ministers met for lengthy discussions in New York. Among other things, Soviet Foreign Minister Andrei Gromyko reportedly told his counterpart that Mr. Arkhipov's visit was still on the diplomatic timetable.
The meetings beginning today could bring a rescheduling of Arkhipov's visit to China, perhaps later this year. If it occurs, it would be the highest-level contact between the two nations since 1969. Such a visit could lead to new trade and other agreements between China and the Soviet Union and perhaps involve the Soviets in China's massive modernization drive.
In the talks, Western diplomats say, the Soviet Union will not give up its strategic gains on China's periphery in order to smooth the way for increased trade and other exchanges. The Kremlin's domestic political difficulties, they say, make any bold moves toward China unlikely for the time being, though a period of somewhat warmer relations is possible.
For its part, China will almost certainly certainly stick to its demands that the Soviet Union remove its threats to China's security.
''How the situation will develop is not up to the Chinese side,'' said Vice Foreign Minister Zhu Qizhen last month in an interview with this newspaper. He was referring to the talks between the Chinese and Soviet foreign ministers in New York, but the comment seems to apply as well to the current discussions.
The Soviet delegation is led by Vice Foreign Minister Leonid Ilyichev, and the Chinese side is headed by Qian Qichen.