Abstract: The prediction of water inflow from coal mining face is the basis for the prevention and control of water in the production process of coal mines. Through the generalization of hydro-geological conditions in coal mine goaf, combined with the analysis of hydro-geological models of various sources and sink items in groundwater numerical simulation software Visual MODFLOW, it is proposed that the water gushing in goaf should be generalized into the boundary conditions of the drainage ditch with the characteristics of planar drainage in the process of numerical simulation. Using the boundary of the drainage ditch and the analysis of the local water balance, the amount of water in the goaf after the mining of the working face can be calculated. Based on the generalized method of goaf in this study, the numerical simulation of water inflow in 303 working face of Tingnan Coal Mine in Huanglong Coalfield is carried out. The results show that the method is reasonable and reliable, and the flow field characterization and water prediction results are better than that from the model of a hole pumping well.