Most of the past studies on the analysis of landslides are evaluated by determinism. It means the analysis are only two results, stable and unstable. However in the real environment, there are a lot of uncertainty factors that would affect the occurrence of landslides. In the study, the authors consider the hydrological uncertainty and the variability of soil parameters of the slope to propose a new method for the risk evaluation of landslide induced by rainfall. The uncertainty has two types, one is the limitation of observation or experiment and the other one is and the error of data. For the landslides analysis, the uncertainty analysis can be separated by the external force from rainfall and the resistance force of slope stability. In considering the external force, it would focus on the analysis the relationship between rainfall and storage by using storage function model based on the uncertainty rainfall and the analysis of slope stability would consider the deviation of the soil parameters. Finally the occurrence of landslides can be summarized as like the risk evaluation during rainfall based on the stochastic process theory.