The earthquake hit the border area between the Chinese provinces of Sichuan, Yunnan and Guizhou at 5.49am local time (8.49am AEDT), at a relatively shallow depth of 13.5km, the USGS said.
There were no immediate reports of damage.
In May 2008 a massive 8.0-magnitude earthquake struck Sichuan killing more than 87,000 people.