The final wave of World Bank economic survey teams in the People's Republic of China returned to headquarters here earlier this month to start preparing the official economic report that will open the way for loans to the world's most populous developing nation and potentially the World Bank's biggest client.

World Bank officials said they hope the report will be ready for the bank's multinational executive board by June. They expect the first project loans -- possibly for transport and higher education -- to be approved shortly after that.

The bank not only has been moving at record speed since May 16 when Peking took over the seat previously occupied by Taiwan, it is thinking big, even for its own mammoth developing lending operations. Officials mention a figure of $10 billion in loans to China over the next five years -- $2 billion a year. This is about half of what China would like in loans but about all World Bank officials think they can manage.

World Bank President Robert S. McNamara told the annual meeting here on Oct. 1 that the addition of China's 1 billion people into the bank's fold would increase the bank's eligible beneficiaries by almost half -- 45 percent. But, in an oblique assurance to such countries as India, which is the world's second-most-populous country and until now has been the bank's single biggest beneficiary ($2 billion a year), McNamara said he hoped the World Bank would be raising enough additional capital to be able to "respond to China's development needs, but not at the cost of its other borrowers."

China has declared that while it certainly wants and needs World Bank loans, particularly the choice no-interest, long-term International Development Association loans (40 percent of which now go to India), it doesn't want to cut into any other country's aid.

From October until now, the World Bank has had some 25 experts in China lifting an economic curtain that has been firmly drawn since the People's Republic was established in 1949. The first surprise was that China is just the opposite of all other developing countries on the bank's roster, which are able to provide national economic data but very little at the local level.

"It makes our project people jump for joy when you can get tremendous detail at the commune level, even down to animal production and slaughter. But it also makes life very difficult for the central economists, because, as a result of China's decentralization, she hasn't done much central planning, and there is hardly any national data," one top World Bank economist reported.

Another surprise for the World Bank teams was China's determination and need for loans to promote higher education. Because of the Cultural Revolution, teachers as well as students were dispersed to till the soil and syllabuses were abandoned. Now the World Bank, which has focused its educational loans in the past on primary, secondary and vocational training, will have to start thinking about helping China develop scientifically equipped laboratories and exchange programs.

Another revelation has been the Chinese desire to be mobile, like Americans, now that new freedoms have replaced the old Cultural Revolution strictures. And for this they want loan money and technological help in building roads, expanding railroads and improving ports.

The World Bank's experts got an earful of China's desire for mechanizing agriculture. But, being economists, they are having to weigh increased agricultural productivity against the unemployment that might result from too many machines intruding on a country with so much available labor.

In addition to education, transport and agriculture, a fourth group of World Bank experts has been evaluating China's desire for help in developing its vast energy potential -- oil, gas, coal, and some hydroelectric. dBut no nuclear power; the World Bank doesn't go in for that.

In gearing up for China, the World Bank so far has allocated surprisingly little manpower to its big new client. The survey teams this fall were nowhere near as large as the huge team that went to India in the mid-1950s under David Bell. The bank's new China section has only five professionals, several researchers and two secretaries here in the Washington headquarters and nobody permanently in the field. Others have been borrowed from the bank's regular divisions. By contrast, the bank's India section has 14 in Washington and 16 based in New Delhi.

One problem the World Bank eventually will have to face is how to divide to IDA pie. These much-sought "soft" loans can be given to any developing country whose per capita income is not over $680 a year. But, depending upon creditworthiness and how far below the cutoff a country is, it has a better chance of getting a "softer blend" of more IDA loans than interest-charging, more conventional World Bank loans.

China first started sending out signals about entering the World Bank more than a year ago. It quickly learned that to become eligible for World Bank membership it first would have to join the International Monetary Fund, and that IMF membership required opening up the economic ledgers, an unheard-of capitalistic peek into a socialistic society. But China's need for World Bank help soon overcame her inhibitions.

Replacing Taiwan proved no obstacle. Taiwan, now a prosperous nation, hadn't done any borrowing since 1972, and the bank's China team actually had been disbanded.