In an uncharacteristic display of irritation, Secretary of State George P. Shultz chewed out a group of American businessman here yesterday, saying if they don't approve of U.S. policies, "Why don't you move to Japan or Western Europe?"

The brush between the working businessmen and the businessman-turned-diplomat occurred in a luncheon interlude during Shultz's second day of talks with Chinese leaders. The secretary of state is attempting to stabilize Sino-American relations, which have deteriorated in recent months.

From such evidence as was made public by the two sides, Shultz seems to have been more successful with his Chinese hosts than with his fellow Americans. Saying that there had been "some rough stretches" in Sino-American relations in the past year, Shultz declared, "I think both sides have navigated successfully and are out in the clear again."

In an unusual meeting with American reporters early today, Chinese Premier Zhao Ziyang displayed a positive approach to Sino-U.S. relations and the Shultz mission.

Zhao said Shultz's eight hours of talks with Foreign Minister Wu Xueqian had "enhanced our mutual understanding" and repeated that China desires "a lasting and stable friendly relationship" with the United States. Zhao cited issues surrounding Taiwan as "the main obstacle" to Sino-American relations but gave no sign that these differences are in an acute stage or that they would interfere with his plan to visit the United States at an unspecified time.

Zhao's comments came just after a meeting of Shultz and Chinese Defense Minister Zhang Aiping. The premier played down the importance of that meeting, saying that "China and the United States have no military ties."

Regarding the high-level Chinese discussions with the Soviet Union, which are to continue next month, Zhao put the onus on Soviet leaders to "make new efforts" to eliminate obstacles to improved relations. He said China hopes for a breakthrough but did not predict that one will develop.

Shultz met the Peking-based American businessmen at the Jianguo Hotel, a year-old Peking establishment that resembles American hotels. Faced with the Americans' complaints of inadequate facilities, lack of U.S. government attention and official policies hampering their sales, the usually even-tempered Shultz let his hair down. He charged that most of the questions addressed to him imply that "there's something wrong with the United States," and he said business rather than the government is often to blame in difficult situations. "Buddy, that's your problem" if the troubles arise from business practices, said the former head of the Bechtel Corp.

The business representatives were taken aback by Shultz's blasts, which came in answer to questions and complaints.

When Shultz sat down, William Clarke, vice president of the National Council for U.S.-China Trade and moderator of the luncheon, remarked, "I can only say that I feel a little bit sorry for Foreign Minister Wu."

The complaint that drew the sharpest retort from Shultz was that U.S. business is unable to obtain export licenses from the U.S. government "when the Japanese and West European competition can get an equivalent license in a relatively short time."

"Maybe they are just better," Shultz responded. "Why don't you move to Japan or Western Europe?" At other points he told the businessmen, as he did the Chinese in the official talks, that the administration has expanded permissible exports to China to high-technology items and that an increasing number of export-license applications is being approved. The field of high technology, where American firms often excel, is of particular interest to the Chinese and to U.S. companies.

The secretary of state was particularly upset by suggestions that a policy change is required in the nuclear export field to permit U.S. firms to compete effectively to build Chinese nuclear power plants.

Pointing out that U.S. regulations are based on concern about the spread of atomic weapons, Shultz said that "the problem of proliferation is a distinct problem and I think the question suggests in a rather cavalier fashion that you brush it off. I don't brush it off."

The Chinese, who exploded their first atomic bomb in 1964 and who have built a considerable arsenal of nuclear weapons, have refused to sign the Nuclear Nonproliferation Treaty or to provide guarantees that they will not assist non-nuclear states with bomb technology.

U.S. intelligence is reported to have obtained information that China is assisting Pakistan's nuclear weapons program, and Shultz is believed to be taking up this issue with the Chinese in his talks. In a banquet toast Wednesday night, he went out of his way to refer to this general issue, saying that "the dangers of nuclear war and nuclear proliferation concern people everywhere and must be among the foremost concerns of their leaders."

According to a State Department official, Shultz, in his talk with Wu, pledged to honor U.S. commitments to gradually reduce arms sales to Taiwan.