With waters on the Yangtze at their highest levels in 44 years, nearly 5 million people in five provinces were mobilized to help ensure embankments held firm, the official Liberation Army Daily said.
An all-out effort was needed to ensure the flood crest doesn't undermine the dikes, already weakened by heavy rains and high waters, the official Xinhua News Agency said.
The flood peak passed Yueyang in Hunan province without incident early Tuesday and was moving through Wuhan, central China's largest industrial center, with more than 7 million residents.
The flood peak was the Yangtze's second-largest since 1954, when floods killed 30,000 people and disrupted life for 10 million others, Xinhua said.
Floods caused by rains that fell heavier and earlier than usual have killed more than 1,145 people so far this year. Almost a million people have been forced from their homes in the three worst-hit provinces: Hunan, Hubei and Jiangxi.
The flooding has prompted direct orders from President Jiang Zemin to local officials to ensure dikes are maintained and victims aided.
In Jiangxi, a bureaucrat responsible for flood control was removed from his post and three others were given reprimands for failing to keep a watch over dikes along Saicheng Lake near the city of Jiujiang, Xinhua said.
Another official in southern Guangdong province was sacked for using an official car to flee with his family ahead of floodwaters, it said.
Construction crews rode rafts to work and residents hurried to dry out belongings during a brief break in the rain Tuesday in Yueyang, a small city on the edge of badly swollen Dongting Lake, which feeds into the Yangtze.
Only the roofs of houses could be seen above the water in the nearby town of Chenglingji, where the Yangtze has breached dikes.
Authorities warn the river could remain at the current high level for up to two weeks, keeping the waterlogged dikes under constant pressure.
Downstream in Anhui province, 2.8 million residents have been flooded out of their homes, and 4,600 hectares (11,360 acres) of farmland have been submerged, Xinhua reported. Television showed farmers ferrying earth on shoulder poles and plugging holes in the embankments with sandbags and wicker baskets full of gravel.
Meanwhile, in China's commercial capital of Shanghai, where the Yangtze flows into the sea, authorities warned that heavy rains combined with dangerously high water levels on the river could lead to "big flooding," Xinhua said.
Torrential rains that began last week have already left some streets in the metropolis submerged and flooded 2,600 homes, it said.
The People's Liberation Army has mobilized a million soldiers to help shore u dikes and has provided 4,000 vehicles and 280 boats to aid relief efforts, Xinhua said. The air force has evacuated more than 300,000 people from flood-stricken areas, it said.
The Red Cross said it was organizing deliveries of food and water purification tablets to victims, and medical workers were striving to prevent an outbreak of epidemics.
Police along the Yangtze were ordered to step up patrols and crack down on thefts of anti-flood equipment, the Liberation Army Daily said. They also were ordered to ensure that prisoners did not escape from detention centers, the newspaper said.
The Finance Ministry, meanwhile, ordered stepped up supervision of flood relief funds to ensure they are not diverted or wasted, the People's Daily said.
Over the past 200 years, the 3,900-mile-long Yangtze has been hit by a devastating flood every 10 years, it said.