A Sino-American summit that would discuss American arms sales to Taiwan and other issues including global strategy seems a possibility following Vice-Chairman Deng Xiaoping's expression of interest in meeting President Reagan.
Mr. Deng, China's de facto leader, raised the possibility during a meeting with visiting United States Sen. Howard Baker. As Senate majority leader, Mr. Baker works closely with President Reagan.
Senator Baker told a press conference here June 2 that he had been ''especially pleased to hear Vice-Chairman Deng say he would like to meet with President Reagan, and indeed he asked me to convey this message to President Reagan. . . .'' He said the details were not for him to arrange but for the President and Secretary of State Alexander M. Haig Jr.
The atmosphere of Sino-American relations has improved following Vice-President George Bush's visit to China early last month. But the difficult problem of American arms sales to Taiwan still ''ticks'' away, in Chinese words, like a ''time bomb.'' Hitherto it had been assumed that President Reagan would not visit China until the arms sales issue has been disposed of.
Now it appears that Mr. Deng, whose formal position is vice-chairman of the Chinese Communist Party (Mr. Deng's protege Hu Yaobang is chairman) would welcome a chance to talk directly to President Reagan about the Taiwan question and other issues.
Senator Baker said he also raised the case of the detention of Lisa Wichser, an American graduate student employed by the Chinese government as a teacher of English in Peking, with Deputy Foreign Minister Zhang Wenjin June 1. Miss Wichser, who is working for a PhD in agricultural economics from the University of Denver, has been accused of having violated Chinese laws and of ''activities incompatible with her status,'' according to a Foreign Ministry spokesman here.
Mr. Baker said he did not know all the details of the case but that he had been assured by the Chinese that they would strictly follow the terms of the Sino-American consular convention. He hoped Miss Wichser would be allowed to leave China as soon as possible.
China wants an American commitment to reduce and ultimately stop Taiwan arms sales altogether. It argues that continued sales violate China's sovereignty.
President Reagan, who campaigned for office saying he would upgrade relations with Taiwan and give the islanders more and better weapons, has gradually changed his position. He now takes greater account of the importance of the strategic relationship between China and the United States in facing the Soviet Union. Since taking office he has restricted arms sales to Taiwan to $60 million worth of spare parts.
But he remains constrained by the Taiwan Relations Act passed by Congress in April l979 following normalization of relations between Washington and Peking. This act provides for the US to supply Taiwan with sufficient weapons for self-defense.
Does the act give the President the latitude to sell or not sell arms to Taiwan, or to cease arms sales altogether? Senator Baker seemed to think that the act as written leaves implementation in the hands of the president with the consent of Congress. Thus there is no need to amend the act, as amendment would also be politically extremely difficult.
However, in his conversation with Mr. Baker June 1 Mr. Deng apparently raised for the first time the possibility of amending the act. Mr. Baker told him he would convey Mr. Deng's remarks not only to the President and to Mr. Haig but also to his senatorial colleagues. However Mr. Baker said he himself did not favor an amendment of the act.