As Reagan plays the China card, Moscow looks as if it wants to deal

This seems to be an appropriate time to remember that Richard Nixon went to China and reopened American relations with that country before he went to Moscow to try to do business there.

That sequence is relevant to these times because it is being repeated intentionally or inadvertently by Ronald Reagan, with interesting results.

Right now there is a good deal of talk about an easing in United States-Soviet relations. The turning point seems to have been a grain agreement signed in July.

Since then, as a sort of quid pro quo, US Secretary of State George Shultz and Commerce Secretary Malcolm Baldrige have joined in recommending to President Reagan that he relax controls on the sale of oil and gas equipment to the Soviets.

The President, according to the New York Times, which printed the report on Aug. 2, is expected to approve the proposal even though it is opposed by Defense Secretary Caspar Weinberger. The report has not been denied in official circles.

Three days later, on Aug. 5, Edward L. Rowny, chief US negotiator in the START talks, disclosed that on July 8 the US had submitted new proposals for strategic arms limitations. The new proposals dropped demands for Soviet reductions which the Soviets would never accept. In other words, the US position was moved from an unacceptable demand on the Soviets in the direction of something they might consider.

Mr. Rowny indicated that the Soviets had responded in kind and that the START talks seem to be moving toward possible agreement instead of being stagnated.

But well before these signs of change in US-Soviet relations occurred there was first a thaw in US-China relations.

Mr. Reagan, be it remembered, started out on a policy of reviving formal US ties with Taiwan and abandoning the opening to China which Nixon had originated and which had been carried on by Gerald Ford and Jimmy Carter.

Reading the record, it appears that he was persuaded with difficulty and only at the end of his second year in office that there might be merit, after all, in the Nixon-Ford-Carter policy toward China.

Apparently he was persuaded - probably in the wake of the November midterm elections, which went poorly for his fellow Republicans in Congress - because Washington's interest in China quickened with the beginning of this year. Secretary Shultz went to Peking in February. The first visible result, on May 5, was a deal between American Motors Corporation and the Chinese government for AMC to build four-wheel-drive vehicles in China.

On May 21 Secretary Baldrige was in Peking just after the signing of a US-Chinese accord which covers cooperation in nuclear physics, transportation, aeronautics, and biomedical technology. This opened up access to scientific information for the Chinese, including the right to purchase high-technology items that could have both civilian and military uses.

On July 30 a seven-month deadlock over US-China trade was broken when the US agreed, reluctantly, to an increase in the US quota for Chinese textiles in return for an increase in the amount of US grain China will buy. A spokesman for the US textile lobby called it ''a disaster.'' It was a concession to China, but there was a quid pro quo, as usual in international relations.

Not only will the Chinese take more grain off Mr. Reagan's hands. On Aug. 6 the Chinese granted drilling rights to two groups of American oil companies. Meanwhile, there is talk of Mr. Reagan's going to Peking and of Chinese Prime Minister Zhao Ziyang's coming to Washington.

By Aug. 6 it was plain to anyone that US-China relations were back on the Nixon-Ford-Carter track. In Moscow, where events of this kind are well understood, it was obvious that Mr. Reagan was not going to repudiate China after all.

A second factor must have entered into Moscow's calculations at about the same time. The US economy was apparently on the mend, and with its improvements went the serious possibility that Mr. Reagan would be president of the US right through 1988.

Hence, that ''correlation of events'' which the Soviets thought to be favoring them a year or so back had shifted. They would have to include in their calculations both a possible two-term Reagan presidency and a continuation and probably steady improvement in US-Chinese relations.

Aiding the process of readiness to do business is a change in the American political picture. Mr. Reagan's managers had concluded in the wake of the 1982 elections that the Reagan image was a bit too warlike. The tone of hostility toward the Soviet Union had apparently frightened more American voters than Soviet leaders. The robes of the peacemaker seemed attractive to him.

Can Ronald Reagan be stern toward Central America and Libya and also negotiate usefully with the Soviet Union?

Probably yes, now that he has his relations with China back on track.

Richard Nixon well understood the importance of the China relationship. He startled the world when he went to Peking. He went almost immediately from Peking to Moscow, partly to avoid the danger that the Soviets might panic and do something reckless, but also to cash in, as he did.

It would have been foolish for the Soviets to do business with Washington this year if they could expect worsening US-China relations. And of course there would be no sense at all for them to do business with a one-term president at the end of his third year.

These are the considerations that count in Moscow, not what Mr. Reagan may or may not do to Nicaragua and the rebels in El Salvador. Soviet investment in Central America is minimal. The costs might seem ominous to Mr. Reagan, but for Moscow they amount to little more than shipping from Vietnam to Cuba and Nicaragua a lot of American small arms captured in Vietnam from the defeated South Vietnamese Army, or simply left behind by the departing Americans.

If Mr. Reagan wants to do mutually useful business with Moscow right now, the Soviets might as well meet him halfway, since he may well be in Washington for another five years and since China obviously thinks it can get more help from Washington than from Moscow.

Thus, the prospects are for still more US-Soviet business, culminating in a meeting between Reagan and Soviet President Yuri Andropov sometime in the spring.