China's economic growth has slowed significantly in several key areas and planners have put off by at least five years ambitious economic targets, according to analysts and candid remarks by a top Peking economist here.

Western analysts here say the slowdown, dramatized by Chinese economist Xu Dixin at a seminar here, shows a Chinese desire to turn away from unrealistic expectations that have caused economic havoc in the past. But the lowered figures appear to put pressure on the post-Mao leadership in China to reduce government savings and increase trade or risk jeopardizing a policy that is keeping them in power, that of raising living standards.

Supplies of cloth remain strictly rationed in Chinese cities and, according to the latest Chinese figures, cotton production in 1979 reached only 2.2 million tons, less than the planned target. The Chinese bought 2.1 million bales of cotton from the United States in the latest marketing year, making them the leading buyer of U.S. raw cotton. A national cotton conference in China in December spotlighted stagnation and deterioration of cotton planting techniques and equipment.

Just a few months ago Zhang Pinghua, first vice minister in charge of the state agricultural commission, had endorsed a grain production target of 400 million metric tons by 1985. Yet at the Hong Kong seminar Xu, director of the economic institute of China's Academy of Social Sciences, said the goal of 400 million tons would not be reached until "the end of the 1980s." China produced 315 million metric tons of grain in 1979, only a 3.4 percent annual increase which would have to be substantially improved to reach the target by 1985.

Sluggish grain production hurts the government's ability to satisfy its growing population of nearly 1 billion. It also cuts into foreign exchange earnings by forcing grain imports. The U.S. Department of Agriculture has concluded that China will import about 10.5 million metric tons of grain from all foreign sources, mostly the United States, Canada, Australia and Argentina, in the 1979-80 marketing year.

Some Chinese economists have argued that imports of grain should continue to feed coastal cities, and production of more light industrial goods, rather than more grain, should be encouraged in order to pay for the grain. This involves a major, somewhat risky recasting of what has been a largely self-sufficient economy into one closely tied to international trade, but the Chinese claim to be having some success. The 1979 Chinese trade deficit increased to $1.8 billion, but this was less than a $3.7 billion deficit prediced at the National People's Congress last June. The Chinese say the difference reflects the success of their export campaign, which they hope will be helped by new most-favored-nation benefits for their goods in the United States.

One analyst here said Chinese officials recently told him they would also seek to continue the increase of personal living standards by cutting the target for government saving, to finance capital inprovements, from 30 to 25 percent of gross national product. The extra funds would be used to raise salaries and provide more local services, like schools, the officials said.

The accent on living standards and light industry has been so great that party leaders appear to have been somewhat annoyed at the steel industry's overfulfillment of its production target in 1979 with a total of 34.4 million tons. The official press has called for less emphasis on heavy industry, charging waste in many parts of the country.

Instead, the emphasis appears to be on reviving the petroleum industry. Despite worldwide publicity about China's huge estimated oil reserves, its major producing fields at Daqing and Shengli will in a few years be virtually drained dry. Total oil production in 1979 was 106.1 million metric tons, only 1.9 percent above the previous years, after a decade in which oil production usually increased more than 10 percent a year. One analyst blamed the decline on "an earlier emphasis on production at the expense of new drilling operations and a lack of essential equipment and skilled manpower."

Chinese oil officials are now actively negotiating with at least one major American oil company for substantial offshore drilling, to follow a similar deal signed with Japanese oil executives recently. Other American firms are also expected to begin drilling offshore in the near future. The Chinese have tried to interest U.S. oil concerns in setting up operations in potentially oil-rich desert areas of China's far west, but have been unwilling to provide the funds and incentives American businessmen feel are necessary to undertake such a risky venture.