The tremor struck southern Xinjiang, a vast region bordering central Asia, at a relatively shallow depth of 12 kilometres (seven miles), the USGS added.
The quake hit near the Tajik border and approximately 172 kilometres west of the Chinese city of Kashgar.
There were no initial reports of any injuries by the state news agency Xinhua.
The Pakistani authorities said the quake had been felt in the northwestern province of Khyber Pakhtunkhwa, the National Disaster Management Authority said. There were no reports of damage.
The USGS said only a relatively small area would have perceived the shaking to be strong.