In the first official Peking comment on a U.S. court decison upholding formal U.S.-Taiwan security ties, a Chinese vice foreign minister said today Washington "should act in accordance with agreements reached for normalization between our two countries."

Vice Foreign Minister Han Nianlong, replying to a question at a press conference, avoided the harsh language Peking has sometimes used in the past when Washington events did not go its way. Moreover, there have been no pointed rejoinders so far to the decision on the official New China News Agency, another preliminary indication of a low-key Chinese response.

Diplomats here say they have detected few if any private Chinese expressions of concern about Wednesday's decision by U.S. District Court Judge Oliver Gasch that President Carter overstepped his authority in announcing the abrogation of the U.S. mutual security treaty with Taiwan without congressional approval.

American diplomats here said that they were not asked for any immediate explanation by their Chinese counterparts. They said that they sense Peking shares the confidence of the Carter administration that the decision will be overturned on appeal.

"There are just so many precedents in our favor," said one U.S. diplomat.

He noted the case of treaties abrogated with Japan at the beginning of World War II without congressional approval and the U.S. Supreme Court's traditional reluctance to reverse presidential foreign policy decisions.

Han spoke at a press conference called to describe the latest unsucessful round of negotiations between Peking and Hanoi. He apparently did not plan to mention the Taiwan issue at all, but an American reporter took the opportunity of a question period to ask what Peking's reaction would be if Congress did not approve abrogation of the security treaty.

Han said, 'Well, I think it much better for the American side, rather than the Chinese, to provide an answer to this question. We should think the American side should act in accordance with the agreements reached for normalization of relations between our two countries."

A steady stream of visitors here from both the Carter administration and the Congress have apparently convinced the Chinese that with or without a Taiwan security treaty, the American government will stick to its commitment in the normalization agreement to limit its support of Taiwan to commercial contacts and the supply of defensive weapons.

Washington has already abided by its two other important pledges under the agreement, by shutting down all official relations with the island -- leaving a shadow U.S. Embassy staffed by temporarily retired Foreign Service officers -- and by removing all U.S. military personnel. Carter has announced he would abrogate the treaty at the end of the required one-year notice, that is, onJan. 1, 1980.

Relations between Peking and Washington are at a high point. From the Chinese view, they were particularly fortified by Vice President Mondale's visit here in late August. Mondale pleased the Chinese, who are eager to hear any comments suggesting Sino-American cooperation against the Soviets by saying in a speech nationally broadcast here: "Any nation which seeks to weaken or isolate you in world affairs assumes a stance counter to American interests."

Since 1971 when preliminary ties between Washington and Peking were opened, the Chines have occasionally given way to public expressions of annoyance at events in Washington that seemed to contradict what they took to be U.S. promises to them.

This continued even after this year's Jan. 1 normalization. In March, when Congress passed legislation with strong language defending Taiwan's security and barring Peking from taking over valuable Washington property held by Taiwan, Chinese Foreign Minister Huang Hua called in American Ambassador Leonard Woodcock. Huang said the bills were "unacceptable to the Chinese government" and would do "great harm" to Sino-American relations.

Diplomats here caution that the Chinese could come out with a stronger reaction to the federal court decision at any time, particularly if it is not reversed as they and the Carter administration expect. But the relatively mild Peking reaction is so far taken here as a sign of growing Chinese sophistication about how Washington works and growing Chinese confidence in the U.S. government's ability to keep commitments made to Peking.

The Associated Press filed this report on reaction to the court decision :

The National government on Taiwan has witheld comment on the decision. The Foreign Ministry noted that Taiwan's opposition to Carter's move was already clear.

The mass circulation, Chinese-language China Times said in an editorial that the suit, filed by Sen. Barry Goldwater (R-Ariz.), and Judge Gasch's decision "are model example of the justice and the U.S. judiciary system's balance of power."