Abstract: On the basis of analyzing the character of the gas emitted from the mining fa ce, the modified Grey predicting model GM(1,1) with amendments to the relationsh ip among the gas amount, mining depth and coal output is respectively establishe d. The amount of gas emitted from mining face could be predicted in case of diff erent mining depth and coal output. The practical application demonstrates that the predicting model is reliable and its precision is enough to meet the practic al usage.