Based on the continuity equation, multiphase gas seepage - diffusion equation and synthesis heat transfer equation in heterogeneous porous media, a numerical model of spontaneous combustion of residual coal in goaf is established under the condition of working faces are being advanced dynamically. Based on an example, the distribution and dynamic procedure of air leakage seepage, oxygen, CO gas, methane and temperature in goaf during working face advancing are demonstrated. For the dynamic advance of working surface, the means of each physical quantity backward step and step is put forward, which can make the moving step suitable for time, so the continuity of simulating calculation is realized. Through theory analysis, it shows that the combustion of residual coal in goal has exponential relation with the speed of working face advancing, so increasing the advancing speed can retard obviously the spontaneous combustion of residual coal in goaf.