During his term, President Reagan has sent two different secretaries of state to China, and each produced what looks like sharply different results. In 1981, Secretary of State Alexander Haig Jr., promised much but delivered little. Relations with China continued to sour.
Leaving Peking on Sunday, Haig's successor as secretary of state, George Shultz, promised little in the way of results but could conceivably deliver more.
The contrast could hardly be more striking. Mr. Haig forcefully asserted that United States and Chinese perceptions had never been closer. Nearly a year and a half later, Mr. Shultz gave a low-key, carefully expressed hope for an improvement in relations.
Even the weather during the two secretaries' visits was markedly different. It was summer during Haig's visit, with the skies often clear. Shultz saw the gray walls and roofs of Peking emerge each morning out of a winter smog. In the winter, dust sweeping in from Mongolia combines with the haze from coal fires to make Peking one of the most polluted cities in the world.
The Shultz approach seems to indicate that a new sense of realism now dominates the American attitude toward China.
In 1981, Haig declared that the US and China ''shared objectives'' on virtually all regional issues. He asserted that the ''common resolve'' of the US and China to coordinate policies in order to limit Soviet expansionism had grown stronger. And Haig predicted ''a major expansion of Sino-American friendship and cooperation.''
But instead of cooperating with Washington against the Soviets, the Chinese opened a dialogue with Moscow aimed at ''normalizing'' relations with the Soviet Union. Instead of expanding, relations between the US and China grew more tense, particularly over the issue of Taiwan.
An agreement on reducing arms sales to Taiwan last August bought time for both sides, but it failed to restore either trust or momentum to the US-China relationship.
It was with the aim of restoring some trust and momentum that Shultz went to China. After four days of talks, progress was made but he did not claim to have solved any problems. Both sides seem to agree that revitalizing the relationship will be a gradual process. As one Chinese with access to high-level thinking in Peking said, ''Three feet of ice were not made in one day's frigidity.''
The Chinese apparently showed no great enthusiasm about American proposals that Defense Secretary Caspar Weinberger make a trip to China this year. Possible arms sales to China were not discussed during the Shultz visit.
In contrast with Haig, who repeatedly emphasized the ''strategic'' relationship between the US and China, Shultz spoke of the US-China relationship as largely independent of the Soviet Union.
''There are aspects of Soviet behavior that affect us both and which we have discussed,'' said Shultz. ''So, I suppose, if you want to call that a strategic relationship, you can, but I prefer myself to think of our relationship as being a stable and enduring one based on the direct contact between the United States and China.
''. . . Our interest is not only on what the Soviets may or may not do but on many other matters of bilateral and international concern,'' the secretary said.
On this point, the Chinese seem to agree. As one well-informed Chinese analyst put it, ''Sino-US relations should not be influenced by Sino-Soviet relations. They are different cases. We don't use this Sino-Soviet dialogue as a Soviet card. We are not going to play the Soviet card against the US.
''The Americans should not be too worried about Sino-Soviet relations,'' he said. ''We will not overdo this . . . .''
He said that the Chinese still considered the Soviet Union ''the main threat to world peace.''
While in Peking, the secretary of state declared that the US and China have ''steered through some rough stretches'' during the past year. But Shultz said, ''I think both sides have navigated successfully and are now out in the clear again.''
The Chinese say, however, that the main obstacle to further navigation may be Taiwan.
A booklet on Chinese foreign policy made available to reporters accompanying Shultz contained an article on US policy toward Taiwan written by Zi Zhongyun, an associate research fellow of the Institute of International Studies in Peking. It says: ''The US attitude toward Taiwan remains a hidden rock on the navigation route, which threatens to run the ship of Sino-US relations aground.''