Abstract: In order to solve the gas source shortage problem of a mine ventilation gas oxidized power generation project in Gaohe Mine of Shanxi Provincial Key Project, a plan to drain the mine gas from the closed goaf to replenish the gas resources was provided and a discussion was conducted on the calculation method and the availability evaluation method of the mine gas reserves in different goaf.The study results showed that the mine gas reserves in Goaf W1303 and W1305 of Gaohe Mine was 508 508 m3 and 1 163 879 m3 individually.The sustainability of the gas drainage was high.But the mine gas reserves in Goaf E1302 was 105 147 m3, the gas reserves was low, the gas drainage time was short and the sustainability was poor.The expected gas drainage time could be a year.After a half year of the gas drainage, there would be a new goaf to be replaced.Therefore，the sustainability of the gas drainage from the goaf could be realized.The method would have important guide significances to the evaluation of the mine gas availability in the initial investment of the gas power generation.