The tremor was recorded at 4:48 p.m. local time (08:48 GMT) near Mannai County in the Haixi Mongol and Tibetan Autonomous Prefecture, with the epicentre at a depth of 10 kilometres.
There are no reports on casualties or damage so far.
Last month, a more powerful earthquake, with a magnitude of 7.4, struck the province. The tremor was recorded on 21 May near Mado County in the Golog Tibetan Autonomous Prefecture. A total of 18 people were injured as a result of the quake.