Some 200 houses have been destroyed in the city of Dandong, and three people are reported missing, state media says.
Flooding has also been reported across the border in North Korea, with the city of Sinuiju severely affected.
More than 1,500 people have died in China in recent months during one of the country’s wettest-ever summers.
In Dandong, floodwater caused a dyke to burst triggering severe flooding in an industrial area. The main railway line out of the city is also reported to have been cut off.
Some 51,000 residents have been taken to higher ground.