While the future of U.S.-Chinese relations remains in doubt, State Department officials have gradually and quietly been expanding their staff in Peking while trimming away some of the China-watchers at the huge U.S. consulate here.

Although sources here say the shifts are routine adjustments not directly related to U.S. policy toward China, they emphasize the growing importance of the U.S. liaison office in Peking as several governments and news organizations debate the merits of Peking versus Hong Kong as a China-watching post.

The British government up to a year ago maintained a highly skilled analysis and radio-monitoring staff here to report on the People's Republic of China, but it was sharply cut back as a result of London's financial crisis.

The Japanese, who severely reduced their Hong Kong China-watching staff when they exchanged ambassadors with Peking in 1972, have since resumed assigning Peking experts here as the Chinese political tumult of the last two years has demonstrated the value of Hong Kong as lookout post.

The shift of official American China-watchers illustrates how important a concession Washington won when the Chinese allowed the United States to establish a U.S. liaison office in Peking in 1973 without requiring the closing of the U.S. embassy in Taiwan. The United States thus gained an important toehold on the mainland that's is almost certain to expand.

Housed in a pleasant but not very spacious Mediterranean-style building in a Peking diplomatic neighborhood, the office maintained about 30 American staff members until the Chinese granted permission to open an annex a few minutes drive away. A liaison office source said that the staff numbered about 32 in December and has since climbed to about 36.

Meanwhile, over the past two years, a U.S. consulate spokesman here said, the American staff in Hong Kong has dropped from about 135 to 130 in an effort to avoid duplication of effort. The cuts have been most noticeable in the busy China-watching section on the consulate's third floor.

A year ago three foreign service officers were assigned to the consulate section analyzing Chinese domestic political developments. Then One was transferred to Peking.

The consulate's section dealing with the Chinese economy was reduced by one analyst this winter when a foreign service officer assigned to watch Chinese foreign trade was transferred to Peking. Officials in Peking and Hong Kong agreed that businessmen traveling though China are easier to reach in Peking and that important commercial events such as the Canton Trade Fair are most accessible to American diplomats stationed inside the people's Republic.

Last year the liason office began to devote more time to reporting Chinese foreign relations, a task that uses official Chinese media reports that are equally accessible in Peking and Hong Kong. The State Department reduced Hong Kong's staff section analyzing Chinese diplomacy from two to one.

Asked if the changes were part of a plan to upgrade Peking as Washington moves toward full diplomatic relations with China, a liasion office source said. "I think that's jumping to a conclusion. We are doing this to provide easier operation more than anything else."

U.S. officials at the consulate here openly discuss their work as promoters of the brisk U.S. trade with Hong Kong, but they discourage any public mention of their China, watching role in order not to offend the Chinese. Still, despite the few reductions in staff, the consulate plays an indispensible role in U.S. policy on China by providing enormous volumes of rapid translations of Chinese broadcasts and newspaper articles.

There are no permanently based American news correspondents in Peking and the Chinese say they will permit none until Washington agrees to full diplomatic recognition. But the ready access to transcripts of Chinese radio broadcasts enjoyed by Hong Kong - based correspondents has at times given them an advantage over Peking-based reporters in covering political troubles in China's provinces.