Abstract: The rainfall is one of the main factors to induce landslides. The percolation process of the rainfall in the landslide mass is described. Some factors are taken into consideration, including change of wetting characteristics of soils, development tendency of the wetting front and transformation between the infiltrated rainfall amount and the groundwater level. The classical Green-Ampt model is coupled with 3D limit equilibrium model, which assumes infiltration area to be saturated and consideres arbitrary rainfall intensity. A real-time evaluation model for infiltration-stability is established based on grid data format of GIS. It can quantitatively assess stability of landslide by the location of the sliding surface. Finally, there are some examples to validate that the proposed method can be employed to assess and analyze the stability of a single landslide.