he heaviest rains in recent years have left large parts of China under water this summer, complicating grain harvests and retarding national efforts to rebuild the economy.

The latest devastation centers on the coal-rich central province of Shanxi where weeks of steady downpours have dropped up to 23 inches in some places, killing 764 persons, injuring 5,000 and leaving 200,000 homeless, the official People's Daily reported today.

The Shanxi rains have inundated 260,000 acres of farmland, killed 8,000 farm animals and swept away 322,000 homes and 230 entire villages, according to the newspaper.

Although there was no indication of damage to coal mines, the paper said 100 landslides along important railway lines have knocked down two of the area's three major power lines and blocked hundreds of central and local highways.

No financial estimates of damage were given, but the extent of devastation cited by People's Daily suggests the need for another large central government grant to salvage farm lands for the late summer harvest and shelter the flood's refugees.

Floods in Shanxi came just as the western province of Sichuan, which is China's biggest grain-producing region, began recovering from devastating rains in July and August that cost, by official estimates, $1.2 billion in direct economic losses.

The Sichuan floods were said by official reports to have caused 920 deaths, left 1.5 million homeless and inundated more than 2 million acres of rich farmland. The storms also wiped out 2,600 factories, official reports said.

Heavy rains have caused serious damage in the northeast province of Liaoning this summer. In late July, 10 days of flash floods destroyed several hundred homes, cut rail links and left farmland waterlogged, according to official reports. There were no casualty estimates given.

Last week, a typhoon swept through the southeastern city of Shanghai, China's biggest city. The typhoon, named Agnes, flooded 55,000 acres of rice paddy and 13,000 acres of cotton fields, officials reported. Nine people were reported killed and 20 injured.

With Chinese officials normally tight-lipped about natural disasters, it is difficult to obtain accurate estimates for the economic damage caused by the summer-long string of calamities.

The recovery costs, however, are considered by foreign experts here to be very high especially for a national economy that is going through a period of retrenchment aimed at wiping out a huge annual budget deficit and correcting high inflation rates.

China is still reeling from the devastating effects of flooding and drought last year in southern and northern provinces. The twin disasters cut grain production by 18 million tons last year, according to official estimates.

The economic losses were so high in the two areas that China departed from its historical policy of self-reliance and asked the United Nations for assistance. Foreign experts estimated losses in the billions of dollars.