According to official state media outlet Xinhua, a gas blast at the Shangchang underground in Yunnan province killed 16 workers immediately – with another dying on the way to hospital.
One of the six injured is in a serious condition, but none are reported to have life-threatening wounds.
Sixty-six people were in the Shangchang shaft at the time of the explosion.
Xinhua said the mine’s owner and manager were in police custody as a preliminary investigation got underway.
The report follows news of a flood in the Furuixiang coal mine of Heilongjiang province, which trapped 16 workers on Saturday night.
Eleven Furuixiang miners are still missing, with three confirmed dead.