U.S. Sen. Ted Stevens (R-Alaska), the incoming deputy majority leader who spent this weekend in high-level talks here, said tonight he would not "rule out" U.S. sales of lethal military equipment to China because of Soviet "aggressiveness" in Poland, Vietnam and Afghanistan.

Stevens, who will head the important subcommittee on defense appropiations when the Senate convenes Monday, said at a press conference that he hopes Soviet leaders will "understand the meaning of my first visit as [subcommittee] chairman . . . and, believe me, it is not accidental that I have come.

"I think we are seeing a new attitude of the Soviet leaders and they have to understand there is a new generation in our country dealing with problems related to them," said Stevens, who traveled to Peking at the request of incoming Senate Majority Leader Howard Baker.

Stevens arrived here Friday with his wife and Anna Chennault, a long-time opponent of the Chinese Communists who was returning to Peking, her native city, for the first time in 32 years. Channault, whose late husband commanded the Flying Tiger air force in China during World War II, came in her capacity as chairman of the Republican Party's Heritage council. c

In its rapidly expanding ties with Peking over the past year, the Carter administration has offered to sell China technology that can be converted to military uses as well as nonlethal military equipment, such as air defense radar, trucks, helicopters and transport planes.

Although many U.S. military planners have urged unrestricted weapons sales to China, a decision has been delayed by counterarguments that sales of lethal weapons would dangerously upset the Soviets, who share a disputed border with China and have conflicting interests with Peking and Southeast Asia.

Stevens, who held talks with senior Vice Premier Deng Xiaoping and Foreign Minister Huang Hua in the last two days, said his discussions included defense questions, Soviet behavior on matters of foreign policy, Vietnam's presence in Cambodia and Peking's relations with Taiwan.

He declined, however, to provide details of his meetings, saying they were "off the record" and would only be revealed in a report to Baker when Stevens returns to Washington after a stopover in Taiwan beginning Monday.

Throughout the hour-long press conference at a Chinese government guest house, Stevens stressed that he was not speaking for the incoming Reagan administration. Nor did he convey any messages from the president-elect to reassure the Chinese about American intentions in eastern Asia, he said.

Chennault, who also attended the press conference, and Stevens chose their words carefully, taking pains to avoid the kind of controversy that erupted several weeks ago when Ray Cline, a Reagan foreign policy adviser, offended the Chinese by statements he made on a swing through Asia.

"We are not here as ambassadors in any way for the new administration," Stevens said. "Since we have not been sent by Governor Reagan, we have not been able to answer questions posed to us [by the Chinese] about what to expect of the new administration.

"We're not here to bring messages to the people of China or bring any messages back."

Chinese officials are still a bit wary of the incoming administration because of Reagan's campaign call for upgrading U.S. relations with the Nationalist Chinese government on Taiwan -- a position he softened after it became a controversial political issue.

Stevens said he told Deng and other Chinese leaders that Reagan is "very realistic" -- a code phrase signifying that the president-elect realizes the advantages of good Sino-American relations as a lever against a common adversary, the Soviet Union.

"We are quite hopeful of expanding and improving our relations with the People's Republic of China," he said. "This country has a great deal to offer in terms of dealing with our country."