In the first incident, authorities confirmed on Friday night that 21 people died after a coal mine blast in the northeastern province of Heilongjiang, the official Xinhua news agency said.
It happened at a private coal mine in Qitaihe city late on Tuesday, trapping 22 workers underground, it said. Rescue work continues to reach the one person left trapped.
On Saturday, 17 people died in a coal mine explosion in northern China's Inner Mongolia region, Xinhua added.
Many others remain trapped, it said, without giving details.