Almost 600 people are now known to have died in the earthquake that hit Yunnan province on Sunday, officials say.
The 6.1-magnitude quake struck a mountainous area, destroying thousands of houses and triggering landslides.
A total of 589 people were killed and nine were missing, China's Ministry of Civil Affairs said. More than 2,400 people were hurt, it said.
Several roads have been blocked and there are concerns about barrier lakes formed when debris blocks rivers.
The quake's epicentre was in Longtoushan Township in Ludian County, a region with steep hills and narrow roads.
China has sent thousands of troops to the area to assist survivors and search debris for any trapped people.
Tents and relief goods are also being brought in both by road and helicopter.
But teams trying to repair damaged roads are being hampered by torrential rain, rockfalls and aftershocks, local reports say.
Officials have also urged volunteers to stay away from the area because the damage to infrastructure means routes that are open are very congested.
Meanwhile, about 4,200 residents have been evacuated from one area because of a barrier lake on the Niulan river.
Waters levels in the lake were rising at a rate of 16cm per hour, Xinhua news agency quoted a technical specialist as saying late on Tuesday.
Sixty soldiers was also trapped by a flood from a barrier lake on Tuesday and had to be rescued, the report added.