Abstract: In order to realize the numerical simulation of coalbed methane reservoir under mining conditions, the geological model of coalbed methane development under mining conditions is generalized, the mathematical model of coalbed methane reservoir under mining condition is constructed, through the secondary exploration of CBM-SIM software, the numerical simulation of coalbed methane reservoir under mining conditions is realized. In the process, the formula of reservoir permeability change curve under mining condition is established based on the formula of variation curve of strata separation, the variation formula of water loss in reservoir is established based on the variation law of water level. By the time card mechanism, the dynamic solution of permeability and leakage water quantity of coal reservoir is made, and the call assignment of coefficients and boundary conditions in the iteration process is solved. The coupling calculation of the dynamic change of permeability with mining influence, the reservoir water leakage and reservoir gas production is realized. By using the software development, the production data of coalbed methane extraction well under mining conditions in Huainan mining area are simulated by historical and yield prediction. The production curve is consistent in shape, and the coefficient of judgment is 0.92. Good simulation results have been achieved.