Chinese leaders, at a delicate moment in Sino-American affairs, thanked former president Carter in person today for restoring full relations after 30 years of estrangement.

At a banquet for Carter in the Great Hall of the People, Premier Zhao Ziyang called the normalization of diplomatic relations on Jan. 1, 1979, "a historic event" and "a major achievement scored by Mr. Carter during his tenure as president."

The former president, on his first overseas trip since leaving office, called his normalization decision "the culmination of a bipartisan effort."

Left unsaid in the carefully crafted public words was Chinese concern about Reagan administration policies toward Taiwan --especially the prospect of high-profile arms sales -- that Peking officials see as a dark cloud over continuing development of relations with Washington.

As part of their increasingly impassioned opposition to U.S. arms sales to Taiwan, Chinese officials have claimed that the Carter administration led them to believe that these would continue only temporarily after normalization. Carter, however, denies making or authorizing any such promise, and U.S. officials familiar with the negotiation record said no pledge of this sort appears.

The Taiwan issue is believed to be one of several factors behind Pe-king's delay in agreeing to specific dates for the proposed visit to the United States of Liu Huaqing, vice chief of staff of the Chinese armed forces. Washington has proposed that the visit, the next step in Sino-American military cooperation, take place Sept. 16-30.

U.S. officials here and in Washington ascribed the Chinese hesitation to:

* Concern that Washington is prepared to deliver on only a few of the 52 items on a Chinese shopping list of weapons and military supplies, despite the Reagan administration's decision in principle to sell arms to Peking on a case-by-case basis.

The Chinese have been asking for definite word, before the Liu visit, on what U.S. arms they will be permitted to buy. The concern is that their military mission will be greeted with more words than action -- in a Chinese metaphor, "much lightning but no rain."

* Worry that U.S. weapons sales to Peking will be followed within a short time by U.S. weapons sales to Taiwan.

Peking authorities are reported to fear that high-profile sales to Taiwan, particularly the sale of a new generation of sophisticated warplanes, could cut the political ground from under those here who are sponsoring close U.S. military ties. A U-turn in military relations with the United States, in this view, could leave China even more exposed than before to the Soviet Union.

Both the Chinese premier and the former U.S. president spoke tonight of the strategic importance, in the anti-Soviet context, of Sino-American cooperation. Zhao also expressed appreciation for President Reagan's readiness "to continue to strengthen" Sino-American relations and expressed "our hope" that this will be done in keeping with the normalization principles laid down in the Carter administration.

Carter, while calling for adherence to the normalization "principles," made no mention of Reagan.

Carter is to see the most powerful Chinese official, party Vice Chairman Deng Xiaoping, at a meeting and luncheon Deng is giving on Thursday. Carter was Deng's host in Washington early in 1979. There is no plan at the moment for Carter to see the new chairman of the Chinese Communist Party, Hu Yaobang.

Carter, who arrived in China late Monday by commercial plane, will spend 10 days in meetings and on sightseeing tours. He is accompanied by his wife, Rosalynn, son Chip, daughter Amy and several aides, including former press secretary Jody Powell.