It may be only a matter of time before Ronald Reagan's foreign policy advisers can sit him down and finally convince him ("Let's take it one more time, Ron") that he is needlessly shooting himself in the foot with his proposal to establish "official relations" with the Chinese government on Taiwan.

It could conceivably happen this week, with the return from China of the governor'srunning mate, George Bush. But there is a long record here, starting in the campaign and carrying through the Republican convention rightup to the past few days. And it is not encouraging.

On the contrary, Reagan's handling of China policy (which is central to his larger foreign policy design) has been very nearly a model of everything -- incoherence, indecision, vacillation -- that he finds fault with in Jimmy Carter's conduct of foreign policy.

Worse, it has encapsulated just abouteverything that we are regularly told we mustn't believe about Ronald Reagan: that he is backward-looking, awash with nostalgia for simpler times, untutored, inflexible and insensitive tothe delicate nuances of diplomacy.

To see why, you must remember by whatslender threads hang the agreement signed on Jan. 1, 1979, to "normalize" full diplomatic relations between the mainland People's Republic of China and the United States. Taiwan was always the sticking point. When Secretary ofState Cyrus Vance began the "normalization" negotiations in the summer of 1977, the opening American bid was for "official relations" betweenthe United States and Taiwan -- a liaisonoffice, in effect, comparable to the ones Peking and Washington maintained with each other.

The mainland government regected it out of hand as "retrogressive" -- exactly the word they use to denounce the Reagan formula today.

And so, in the hard bargaining that followed, an unprecedented arrangement was worked out: the United States would create a "private"foundation, the American Institute of Taiwan, financed as a line item in the State Department budget to the tune of $7 million annually. State simply turns the money over to the Institute, which operates rather like a consulate -- without an Americanflag.

Peking accepts this an "unofficial" because we say that's what it is.

For months now, Reagan has been crashing around like a bull in this diplomatic (forgive me) China shop. More than once in the course of the campaign he promised to upgrade U.S.-Taiwan relations. Specifically, he spoke of "official relations". Repeatedly, the Peking government has responded with public and private warnings of serious repercussions if the Taiwan arangements are tampered with.

"If the United States should restore so-called official relations with Taiwan," the Peking Daily said on behalf of the Chinese government the other day, "it would essentially violatethe basic principles for the normalization of relations between China and the United States and would be bound to affect the normalization of relations between the two countries."

Hanging in the balance is not just the welfare of Taiwan, which Reagan obviously cares deeply about. At stake, as well, are the larger geopolitical, power-balancing concerns that led Presidents Nixon, Ford and Carter to find an advantage for the United States in the big trouble that "normalization" of U.S.-Chinese relations means for the Soviet Union.

Washington's China-watchers insist the arrangements with Taiwan are working tolerably well. U.S.-Taiwan trade is way up. The mainland Chinese have gone out of their way to ease tensions and promote contacts with Taiwan.

Reagan's chief foreign policy advisers must know that. Indeed, at the Republican convention they were at great pains to reveal that the governor had just been thoroughly briefed on China/Taiwan issues and that he had nointention of upsetting existing relationships.

You would also expect George Bush to know it. He is so proud of his 1974-1975 tour as head of the U.s. liaison office in Peking, and of his China expertise, that he turned down an offer of a StateDepartment briefing before his trip. "I know these $ people" is the way he brushes off questions about Reagan's China policy.

Yet when Reagan was sending Bush off to China the other day, there he was insisting, as if it settled everything, that all he had in mind was "an official government relationship". Asked if that was the message Bush would take to Peking, he replied: "i don't know. I hope I haven't put you in a spot, George, with that."

And then last Friday, even as Bush, in Peking, was trying his hardest (apparently in vain) to convince the Chinese that no change was contemplated in this country's Taiwan arrangements there was Reagan, in Dallas, holding fast to the idea of an "official" government liaisonoffice.

Watch what we do, not what we say, the Reagan people keep telling us. But Reagan was doing something when he dispatched his running mate as his envoy to Peking.