Abstract: Previous researches have shown that the evaluation of the landslide induced by rainfall is accurate or not, depending on the ability of how to describe the process of the rainfall infiltration. The modeling calculation of the unsaturated zone in the Sanzhouxi landslide induced by the rainfall are carried out by using HYDURS-1D. The simulation results are compared with the actual monitoring results. The results show that the evaluation of the regulation of the landslide by using Hydrus-1D is reliable. The lag time of rainfall penetration recharge to groundwater is influenced by the rainfall characteristics and the initial water contents. On May 25th and May 29th, it spent 6 h and 19.2 h respectively for the wetting front to arrive to the bottom of the model. The results of the actual case can help us grasp accurately the rainfall infiltration of the landslide. They are of great significance in the evaluation of the stability of landslides under the condition of rainfall.