Abstract：The mathematical model of rainfall infiltration on the rock slope and the numerical simulation method for this model is discussed. Based on this，the system of nonlinear equations in saturated-unsaturated seepage model is researched. The solution method and process of the system of nonlinear equations with Picard iteration method is given. The pattern of rainfall infiltration on the rock slope is analyzed. The variation of matrix suction，the formation and development of transient saturated zone，and the distribution and variation of transient water pressure in the process of rainfall infiltration on the rock slope are described. All the stages of rainfall infiltration on rock slope in a given open pit mine is simulated with the presented method.
