The quake was centred in a remote mountainous area, where much damage was expected to ordinary homes. Rescue teams were trying to reach affected areas.
The China Earthquake Administration said the quake registered a magnitude of 6.6, at a depth of 10 kilometres.
Reports said there was at least one person confirmed dead, and about three dozen injured.
The geologically unstable south-western region has suffered several strong earthquakes over the last decade, causing thousands of deaths.