U.S. Defense secretary Harold Brown arrived here for talks that he said have gained added significance" since the Soviet invasion of Afghanistan. A senior U.S. official traveling with Brown added that the United States hopes to "go from passive to more active forms of security cooperation" with China.

The senior defense official speaking to reporters on Brown's plane before we landed here this evening said increased military aid to Pakistan from both Peking and Washington to counter the Soviet threat would be "an example" of "parallel action." He declined to specify, however, what particular kinds of military cooperation Brown would actually be discussing with the Chinese.

Brown was greeted at Peking's airport by Vice President and Politburo member Geng Biao, along with several other Chinese officials, at the start of his week-long visit. The Chinese are clearly eager to talk about the situation in Afghanistan, which they see a clear proof of their repeated warnings about Moscow's aggressive instincts. During the last few days the official Chinese news agency has devoted space to little else but the Afghanistan situation and world reaction to it.

On the plane, Brown noted that his visit on China had been scheduled months ago, "but clearly what's happened in Afghanistan gives the visit an added significance." Brown said he was "sure that both sides in the talks here will discuss the invasion and necessary reactions that each of us will be taking."

Asked if closer cooperation meant U.S. sale of arms to China the senior official traveling on Brown's plane said. "Our position on that remains that it had been, we have no plans to sell arms" to China.

Although the senior official was reluctant to compare current U.S. relations with China to U.S. relations with the Soviet Union, he indicated that at the moment Washington was more willing to discuss sale of high technology to Peking than to Moscow.

"It would be foolish for us not to behave differently toward the Chinese and Soviets since they behave so differently toward us the official said.

As a possible measure of the importance the Chinese now put on cooperation with the United States, Peking has been slow to issue, what American diplomats expect will be a protest of Thursday's State Department announcement of the resumption of arms sales to Taiwan.

The senior official, apparently speaking before the release of the text of President Carter's address on the Afghanistan situation, declined to describe specific U.S. responses to the Soviet invasion, but said, "We are not about to get engaged militarily in Afghanistan."

The official hinted at the government's plan for accelerated arms shipments to Pakistan as announced by Carter. When asked if the United States planned to provide arms to Moslem insurgents fighting to overthrow the Soviet-backed regime in Kabul, the senior official declined to discuss the subject.

"China is a nuclear power and is assuming an increasingly active world role. . . and we want to give security relationships all over the world a certain predictability and stability," said the official, in explaining reasons for the first visit here ever by a U.S. defense secretary.

Asked about the chance of a quick Soviet withdrawal from Afghanistan the senior official said Moscow had promised to withdraw from Czechoslovakia after its 1968 invasion there, but still had five divisions in the Eastern Europe country.