The official Xinhua news agency reported on Thursday that nearly 700 miners were underground at the time of the explosion at the Sihe coal mine in the northern province of Shanxi on Wednesday.
The report cited an unnamed official with the provincial coal mine safety supervision bureau that 53 people were hospitalised after breathing toxic gases from the blast.
Search and rescue work ended early on Thursday.
The government has been trying to clean up China's mining industry, which killed more than 5500 in the country in 2005, but a spate of accidents has made a mockery of safety campaigns.
Booming demand and high prices for coal, which accounts for about 70% of China's energy, mean that regulations are often ignored, production is pushed beyond safe limits and mines that have been shut down reopened illegally.
China produces about a third of the world's coal but accounted for more than 80% of global coal mine deaths in 2004 and the death rate at its mines is 100 times that for pits in the United States.
Shanxi, where Wednesday's blast happened, is China's leading coal producing province, and has shut about a quarter of 1200 mines targeted to be closed because they lacked proper safety measures, according to a report from the National Development and Reform Commission.