The invention discloses a method for predicting the gas emission quantity of a working face under the pressure relief condition. The method comprises the following steps: a, determining the gas emission compositions of a stope face, which comprise coal wall gas emission, falling coal gas emission, gas emission from residual coal in goaf or/and adjacent-layer gas emission; b, respectively calculating the emission quantities of all gas emission sources; c, according to the emission quantities of all the gas emission sources, calculated in the step b, predicting the gas emission quantity of the stope face, and building a gas emission quantity prediction mathematical model under the exploitation condition of an underlying remote protective layer. The method solves the problem of inaccurate gas emission prediction of the stope face under the pressure relief condition, so as to better guide safe mining of the working face.