The miners were killed when a gas explosion ripped through the Gaoping coal mine in central China's Hunan province on Sunday, the State Administration of Work Safety said on its website.
The other 25 miners were trapped after an explosion at a coal mine in northern China's Inner Mongolia region on Monday morning, state media said.
Thirty-three workers were underground when the Inner Mongolia blast occurred around 4am (2000 GMT Sunday) at the Rongsheng colliery in Otog Banner, the Xinhua news agency reported.
Eight workers were rescued but the rest of the team remained trapped, it said.
China's mines are the world's deadliest with around 6000 miners dying in accidents last year, according to government statistics.
Labour rights groups say the actual figure could be as high as 20,000.
The Chinese government has been struggling to improve safety in the nation's mines in recent years. China's booming economy has led to increased output of coal, the country's main source of energy.