Can China cut population by 30% in 100 years?

China has mapped out an ambitious program of population control. The aim is to stop growth by the end of the century, then gradually bring population down until it stabilizes at 650 to 700 million people 100 years from now.

At a United Nations-sponsored conference on population and development here last week, delegates paid tribute to Chinese successes achieved so far - and to the current one-child-per-couple movement.

Even with this drastic program, China's population in the next 20 years will grow by as much as the present population of the United States. By 2000 it could reach 1.2 billion.

In a speech to the parliamentarians' conference, Chinese delegate Lu Qingchang noted that already ''China's population approaches 1 billion, constituting 22 percent of the world's total population.'' He expressed the hope that this population would not grow beyond 1.2 billion by the end of the century.

The Chinese leadership admits that the goal cannot be easily achieved because , in Vice-Premier Chen Muhua's words, ''The old concept that 'the greatest filial impeity is failure to produce male offspring' is still current among large sections of the people.''

So far only 10 percent of couples of childbearing age have responded to the call for one child per couple, Mrs. Chen said.

She was quoted in an interview with the offficial New China News Agency on the eve of the population conference in the Great Hall of the People.

But if people, particularly in rural areas where four-fifths of all Chinese live, can be persuaded without exception to have but one child per couple by 1985, then, from 2000 on the fertility rate could be raised to 2.16 per couple, population expert Song Jian estimates. That should bring down the population level gradually to around 700 million by 2070 and to the 650-700 million range by 2080.

If this is too drastic a program, Mr. Song suggests that at least every effort be made to limit births to 1.5 per couple by 1990 and to keep it at this level until 2025. This would mean the population would not come down to 700 million until the end of the next century.

Vice-Premier Chen, the only woman on the party's Politburo, admitted that in implementing the one-child-per-couple movement, ''Some comrades work in an oversimple manner and cause resentment among the masses.'' In other words, they try to force compliance.

A recent newspaper article pointed out that current government economic incentive policies of paying more for more work means that peasants often prefer to have large families. This is because the more workers a family has, the greater its earnings will be.

There appears to be no intention by the government to change the incentive policy, which has brought about a measurable increase of prosperity in the countryside.

But it is not easy to solve the contradiction between the economic incentive to produce large families and the need for China as a whole to drastically reduce population growth as quickly as possible.

However, Mr. Song argues forcefully that even if the optimum population of 700 million or so cannot be achieved for another century, it is absolutely essential for the one-child-per-family program to be carried out consistently for the next 20 years.

He cites three reasons 700 million is optimum. First, as China modernizes and mechanizes, the agricultural work force can decrease to 60 million (from 300 million today), while the industrial work force will increase slightly to 120 million (from 100 million today).

Mr. Song says studies of modernized societies show that to support an agricultural and industrial work force of 180 million, the total working-age population should be 488 million. Mr. Song does not explain these calculations. But he seems to be thinking in terms of a major increase in the commercial and service sectors of the work force, which at present are small. Total population, in turn, should be between 650 and 700 million.

Second, a century from now China's agricultural production will be about 150 percent of today's level of 330 million tons of grain per year. To bring the protein intake per person per day from 56 grams (today's level) to a more desirable 85 grams per day, the optimum total population should be 680 million.

Third, China today has only 5.5 percent of the world's supply of fresh water, although its population is 22.7 of world population. To maintain adequate industrial, agricultural, and personal water supplies, population should not exceed 650 million.

Mr. Song's suggestions are published in a book entitled ''China's Population: Problems and Prospects,'' published in English by the New World Press here on the eve of the population conference. Mr. Song has expressed some of these ideas publicly before. But his article ''Population Growth - Development and Plans'' is new and was written expressly for the book.