Peking — As China's relations with Washington cool over Taiwan, Peking seems to be distancing itself from the Reagan administration in other areas of foreign policy - at the United Nations, in the Middle East, in Africa.
The contest over the secretary-generalship of the United Nations gave China the opportunity to present itself as a champion of third-world interests. Peking supported Salim Ahmed Salim of Tanzania until agreement was reached on Peru's Javier Perez de Cuellar. This blocked the two superpowers, Washington and Moscow , from obtaining another term for Kurt Waldheim.
In the Middle East, China supported the Saudi peace plan, even though Saudi Arabia recognizes Taiwan. China has been disappointed by American lukewarmness to this plan.
China shares the American evaluation of the Soviet Union as an expansionist troublemaker in the Middle East. But it is impatient with Washington's pro-Israeli stance.
The Chinese regard the Reagan administration's relatively conciliatory policy toward South Africa as another blind spot.
Peking was considerably embarrassed by recent allegations that it had sold uranium through Swiss intermediaries to South Africa. In denying them, Peking came close to suggesting that there had been collusion between Washington and Moscow.
''Recently, Washington and Moscow performed a duet in spreading the lie about China selling nuclear fuel to South Africa,'' said a New China News Agency commentary earlier this month. Vice-Premier and Foreign Minister Huang Hua has just completed a tour of West African countries during which he repeatedly sounded the theme that superpower rivalries between Washington and Moscow were responsible for world tensions.
In all this China comes closer to reflecting a third world view of criticizing both superpowers rather than concentrating exclustively on the Soviet Union.
The shift in China's foreign policy is more nuance than 90 degree turns. The theme of third-world solidarity has always been present.
The lumping of the US and the USSR as egotistical superpowers is not new. But it had been much rarer since the 1978 Chinese-American normalization - and especially since the late 1979 Soviet invasion of Afghanistan. The revived theme thus suggests a definite cooling of Chinese-US relations.
There are no discernible domestic reasons for these general shifts. Some diplomats maintain Deng is in deep domestic trouble. But the majority view is that politically Deng is unassailable and that only if his domestic economic policies fail would significant opposition develop. In foreign policy Deng is thought to have a relatively free hand.
In sum the main explanation lies in Chinese uncertainties over the direction and consistency of foreign policy under the Reagan Administration.
From Washington's perspective, the biggest unknown amid these changing nuances of Chinese foreign policy remains the future course of Sino-Soviet relations. Diplomatic observers here see no signs of a real thaw.
Even a major rift between Peking and Washington over Taiwan seems unlikely of itself to change the adversary nature of the Sino-Soviet relationship. Moscow remains a security threat to Peking - in fact, the security threat to Peking.
The prickliness of Chinese-American relations over Taiwan lies in the fact that Taiwan has domestic political implications in Washington and Peking. In both countries, domestic politics assume an immediate importance sometimes overriding fundamental long-range strategic interests.
But for China, the question of Taiwan is also one of fundamental long-range strategic interests. On Taiwan, China will act or react as matter of national pride and sovereignty.
On the Soviet Union, however, Chinese actions will be governed by considerations ultimately involving national survival. What Peking does or does not do regarding relations with Moscow will be governed by many more factors than anger over continuing American arms sales to Taiwan.