Taipei — Peking's peace offensive against Taiwan has been greeted with deep suspicion on this island of 18 million people.
A letter written by Liao Chengzhi, a deputy chairman of the National People's Congress, proposed peace talks to President Chiang Chingkuo. But it is regarded here as a propaganda exercise, not a serious offer of negotiations.
''If Peking is serious,'' said a Taiwanese journalist, ''it would be talking to the leaders here in private, and not making all these public gestures.'' He was referring, not only to the Liao letter front-paged by the People's Daily July 25, but to Marshal Ye Jianying's nine-point peace plan published last September and subsequent invitations to various prominent personalities here, including President Chiang, to visit the mainland.
Official reactions are even stronger.
''Unless we can remove our ideological differences,'' said Dr. James Soong, director of the government information office, ''there is no chance of talking about negotiations.''
Dr. Soong said in a recent interview that the pragmatic economic policies now apparently being followed on the mainland would have to be ''the beginning of many changes'' before Taipei could talk with the Communists.
Suspicion of Peking's motives is widespread not only in government circles but among the population at large, the vast majority of whom are Taiwan-born. In the minds of many islanders, Peking's peace offensive is linked to the strong pressure the Chinese leadership is exerting on the United States to reduce and eventually to cut off its arms sales to Taiwan.
One experienced Western political analyst here says he thinks this pressure is an attempt to bring Taiwan to the bargaining table in the weakest possible position. The Reagan administration has already reduced arms sales to Taiwan to a level far below that of the previous Carter administration. A commitment to cease all arms sales would be seen by most islanders as a sellout.
''The Communists assume that the more arms the United States gives us, the more Taiwan will move toward separateness or toward independence,'' said a young Taiwanese political scientist and editor. ''This assumption is wrong. The more secure our government and people feel, the more ready we will be to talk.
''We don't want political ties with the mainland,'' he said. ''But we would be interested in increasing economic ties.''
Already there is considerable trade between Taiwan and the mainland. Taiwan goods reach the mainland legally through Hong Kong and illegally through fishermen smuggling goods on both sides of the Taiwan strait. Chinese medicines and other traditional goods can be bought in Taiwan, while Taiwanese television sets, tape recorders, and other consumer goods are in great demand on the mainland.
If the status quo could not continue, said a Taiwan businessman, he would be willing to accept the status of ''special autonomous region'' that Peking is offering Taiwan - as long as this meant that Taiwan could continue its present economic and social system.
''What would be ideal, under those circumstances, would be a status akin to Hong Kong,'' he said. ''Everyone in Hong Kong admits that he is a Chinese. But the political, economic, and social structure remains entirely separate from that of the mainland.''
Many political observers on Taiwan do not share this businessman's viewpoint. Suspicion and fear of the Communists is pervasive.
''I've been to Hong Kong and Singapore,'' said a farmer's wife in Taoyuan, ''but I have no interest whatsoever in visiting the mainland.'' Her family owns a car, several motorcycles, a color television set, and air conditioners in the bedroom - all unimaginable luxuries for most mainland peasants.
''We all agree we're Chinese,'' said a mainland-born intellectual. ''But during the 30 years that we have been separated, our social and economic systems - and even our political systems - have diverged so much that it is going to take a very long process of growing together before we can achieve reunification.''