Abstract: Aiming at this dynamic process that the infiltration will be occurred when the rainfall runoff flows down from a slope surface and the caused increase of soil water content in an unsaturated zone, the soil water and surface water were coupled from the physical mechanism in this paper. A two-dimensional plane model of the surface water was superimposed on top of a soil water model, and the same spatial and temporal discretizations were maintained for both models. In addition, during the calculation process for the models, the water exchange between the surface and soil water was calculated (double node analysis coupling) or a global approach integrating the discretization equation was coupled. Comparing the two coupling methods and compared with previously published experimental results, the model and coupling method in this paper can be used to accurately simulate and predict the movement processes of surface runoff and soil water. The research results of this paper can provide theoretical support to analyze surface water flow and the coupling mechanism of the water content and solute between saturated and unsaturated zones.