Heavy rain has left 128 people dead and 42 others missing in five days, figures from the Ministry of Civil Affairs showed on Tuesday.
Rain since June 30 has led to the collapse of 41,000 houses and forced the evacuation of more than 1.34 million people, mostly along the Yangtze River and its tributaries.
Nearly 600,000 people are in urgent need of basic living assistance, with 23.3 million threatened by floods.
The rain has destroyed 295,200 hectares of crops.
Floods and landslides are also affecting telecommunication and electricity facilities, halting or delaying traffic in some regions.
The ministry estimated total economic losses of 38.2 billion yuan (5.7 billion U.S. dollars).
The ministry and the National Commission for Disaster Relief started a level-four emergency response in Hunan and Guizhou on Tuesday afternoon and sent teams to help relief work.
Guizhou has been one of the worst-hit provinces, with 44 dead and 20 missing in floods and landslides.
In Hunan 11 people have died.
Hunan upgraded its emergency response to level-two, sending 30 million yuan in cash, food, clothing, tents and quilts to disaster-hit areas.
In Hubei, heavy rain has left 45 people dead and 11 missing, local civil affairs department said. Direct economic losses are estimated at 15.5 billion yuan.
Flooding has disrupted traffic on 10 highways and more than 20 trains were delayed when a boat rammed into a pillar of a railway bridge.
Days of heavy rain has raised water in about 700 km of the Yangtze River from Jianli to Nanjing above the warning levels, but there are no reports of breaches on the main embankment, said Chen Guiya, an official with the Yangtze River Water Resources Commission.
Several small rivers and fish ponds in Hunan and Hubei have overflowed, inundating farmland and forcing the evacuation of tens of thousands of people.
Heavy rain was waning in the middle and lower reaches of Yangtze River on Tuesday and Wednesday, bringing respite to the region, but a new round of torrential rain is expected in the coming days.
South Korea expecting attack from intentional flooding as North Korea dam is bursting with 400 million tons of water
"It never happened before!" A waterspout tornado hits Cuban capital injuring 38 people and damaging dozens of buildings
A real "Day After Tomorrow"on the cards as the Jet Stream, the Gulf Stream both stutter and a Solar Minimum on the way!
A "one-in-a-thousand-year event": Rivers reach historic highs as federal disaster declared across West Virginia: 24 dead
Lake Isabella fire is out of control and has turned deadly: Blaze has grown to nearly 47 square miles since yesterday
100 dead 500 people injured, 200 of them critically after massive tornado hits Yancheng Province of Jiangsu China
Nearly one million people evacuated as almost entire month of June ave rain falls over night in Southern Japan
Half the June average of rain fell in London in just one hour causing flash floods and travel chaos on EU referendum polling day.
For the 13th consecutive month in a row (May) was the record warm month across the globe: But how bad can it get?