The blast occurred in the Daping Mine in Henan Province, when 446 people were at work. It was China's deadliest mine disaster this year.
Sun Huashan, deputy administrator of the State Administration of Work Safety, said 298 miners escaped alive. More than 1,000 rescuers were searching for the missing 86.
Most of the miners whose bodies had been found had died of suffocation in the toxic fumes. The gas density in the mine's atmosphere shot up from 2 percent to 40 percent in less than three minutes.
"The chances of the workers surviving are rather slim," Sun said at a news conference in Beijing.
Twenty injured miners were hospitalized, four of them in serious condition.
State Councilor Hua Jianmin said the government will try its best to find the missing, treat the injured, prepare compensation for families and uncover the cause. All coal mines in the country will conduct self-inspections on workplace safety to minimize potential risk, he said.
China's coal mines are the world's deadliest, with thousands of deaths reported every year in explosions, underground floods and other accidents often blamed on negligence or lack of safety equipment.