Chinese authorities, for the first time in 20 years, have disclosed the officials estimate of China's population and have revealed plans for a colossal headcount next year.

The Chinese officials, speaking to American visitors in Peking, put the 1977 population, including the independent island of Taiwan, at 960 million. Even subtracting Taiwan's then 16 million, this would be nearly one quarter of the world population of about 4 billion, 3.7 times the Soviet Union's population and more than four times the U.S. population.

A census of the Chinese population would help solve the great demographic mystery about the size of the world's most populous country and, more importantly, give China information crucial to solution of its severe feeding and housing problems.

Since 1959, Peking has made only vague and inconsistent references in official news stories to its population, in recent months referring sometimes to 800 million and sometimes 900 million.

Officials of the State Statistical Bureau disclosed the plans for a 1980 census to Courtenay M. Slater, chief economist of the U.S. Commerce Department, who was traveling in Peking with Commerce Secretary Juanita Kreps. The first and only census previously reported by China's Communist government was in 1953, when the population count totaled 582,603,417.

Slater said the Chinese expressed interest in exchanging information with the United States on how it conducts its decennial census. The 1953 Chinese census was carried out between midnight June 30 and midnight July 1 by 2.5 million officials, students, party leaders and other personnel specially trained for the task, the Chinese press said. Peking estimated at the time that the census takers missed only 0.116 percent of the population. A U.S. Census Bureau expert, John S. Aird, has said the error was probably at least 5 percent, or 29 million people.

Of the current population, Slater said in an interview, "Nobody really knows how many people there are, but this [960 million] is the estimate the government now uses"

She said the bureau officials, including director Chen Xian, said the 1980 date for a new census was preliminary while they determine what preparations are necessary.

Slater said she asked the Chinese about vague references in the official press to a 1964 investigation of population totals and was told a census was conducted that year also. The officials gave no other significant information about that census, however, and maintained their silence on the total population recorded then.

According to an article by Aird in a recent report on the Chinese economy by the U.S. Joint Economic Committee, Peking's State Statistical Bureau has released no useful population estimates since the late 1950s. The last official figure, for the population as of Jan. 1, 1958, was 646,530,000.

After that, the official Chinese media would occasionally give provincial population figures, but "for the most part, the figures cited tended to be repeated year after year without change," Aird said. "By the middle 1970s, the public citation of provincial figures had virtually come to an end."

Slater said bureau officials gave a current population growth rate of 1.2 percent. The official press had reported this figure, along with claims that in at least 10 large cities or provinces, population growth has fallen below the official 1980 target rate of 1 percent.

Some foreign analysts accept these figures: others are skeptical. Using the official Chinese figures for 1953 and 1977, the annual growth rate would be 2.58 percent for that period. That is an average and most analysts would agree that the over-all growth rate is lower than that now.

Using the official Chinese growth rate, the Chinese population would now be 966 million, not counting 17 million people on Taiwan, and would pass the billion mark in 1982. Some foreign analysts, including Aird, estimate it has already passed that mark.

Taking an accurate count of the Chinese population is a staggering task, not only because of the sheer numbers but also because 80 percent of the population lives in scattered farming communities, many extremely remote.

In urban America "we probably missed about 5 million people in the last census," Slater said.

Chinese leaders, including the later Chairman Mao, have complained of peasants purposely overreporting family size to acquire more grain and other goods. In cities, several Western scholars have noted that some workers violate restrictions on growth and bring their families in to live with them, not reporting the extra relatives. Thousands, perhaps millions, of youths are known to have deserted jobs in rural areas to return to the cities and try to avoid registration.

Slater noted that population registers for each family are kept by local police officials who are not interested in the data needed by state economic planners. Peking, conscious of China's population problem, has begun to experiment with harsh limits on salary and housing for parents who have more than two children and rewards for those who have one child or none.

Grain production has barely kept pace with population in recent years. Acording to one official report, per capita grain distribution is actually less than it was 20 years ago. The official press now points out the benefits population control can have on living standards.

In the last years of Chairman Mao, who died in 1976, the population problem often was ignored and Peking bragged of the power and invulnerability to attack provided by its huge population.