A major irritant in Sino-American relations has been eased by President Reagan's decision to allow high-technology sales to China. The sales will be subject to guidelines that are yet to be worked out. But Western diplomats here say that the classification of China in the ''V'' category, that is, in the same category as friendly non-allied countries such as India and Yugoslavia and even allied countries such as Great Britain and France, is significant.
Whether sales of high-technology items to China will rise to $1 or $2 billion per year remains to be seen. For the present such sales are estimated to be around $200 million per year. The high-technology items include semiconductors, telecommunications equipment, computers - especially in petroleum engineering applications such as seismic surveys and data processing - and other dual-use technology.
Some Western diplomats think that, because of China's increasingly sophisticated requirements in telecommunications and in the petroleum industry, a steep rise in high-technology sales is entirely possible.
This technology is called dual-use because although it is designed for civilian purposes it can be applied to military uses. In China's case, the Carter administration made the basic decision to sell China such technology. The Reagan administration implemented this decision after former Secretary of State Alexander Haig visited Peking in June 1981.
At that time a special category, ''P'' was created for China. The administration decided to sell China technology which was two times as sophisticated as technology approved for sale to the Soviet Union. The application of this decision was cumbersome, however, and led to long delays in the sale of such items as United Nations-financed computers for use in China's 1982 census.
Thus high-technology sales developed into one of the two major irritants in Sino-American relations, the other one being American arms sales to Taiwan. The arms sales issue continues to smoulder. But the easing of restrictions on high technology is bound to improve the general climate of Sino-American relations, diplomats here believe.
Other irritants in Sino-American relations are the dispute over textile import quotas for China, over railway bonds issued in 1911 by the defunct Manchu dynasty, and over the granting of political asylum to tennis player Hu Na.
The Hu Na case is closed, although its aftereffects remain, in Premier Zhao Ziyang's words. There is a possibility of movement in the railway bonds issue, where the US has sent a delegation to explain American legal practices to the Chinese. (Essentially, China refuses to accept the jurisdiction of a court which awarded $42.5 million to American owners of these bonds.)
The textile dispute is to be taken up once more in July, when both Americans and Chinese hope for a final agreement. Thus the prospect is that Sino-American relations will slowly improve after a long period of decline.
Relations between Peking and Washington under the Reagan administration cannot really be called warm. But there seems to be a conscious effort on Peking's part to keep disagreements in one area from spilling over into another. President Reagan's decision is helpful in this regard.
One caveat remains to be made: The guidelines defining what China may or may not buy are yet to be drawn up, and if they are perceived by the Chinese as being overly restrictive there could be a backlash. Hitherto the Defense Department has been cautious toward high-technology sales to China, while the Commerce Department has been promoting them.
But in a comment on the President's announcement, Defense Department spokesman Henry Catto described China as a ''friendly, modernizing country with which we have common strategic objectives'' and said, ''We support the liberalization of sales to China.'' Western observers here hope the guidelines will reflect this sentiment.