Abstract: Using FEM， mathematic models for porous medium in underground flow and on surface flow respectively, as well as their combined model were established. Corresponding FEM analysis calculation programs were compiled. The permeation flow model and surface runoff model were verified respectively. Under practical rainfall intensity curve condition, the simulated results of outflow process from slope toe and the variation process of infiltration rate were given. Calculation shows that these models provide more accurate water load for evaluating the stability of landslide and possess certain practical engineering value.