Based on the assessment of susceptibility degree, the geology circumstance, geographic background and climatic factors, the zonation of the landslide and debris flow is carried out. And the research area is divided into 6 sub regions: the western part of Loess Plateau, Qinling Mountains, Daba Mountains, Dabie Mountains, Luoxiao Mountains, and Zhejiang Fujian coast. The plotting of effective precipitation and landslide/debris flow shows that effective precipitation is among a certain range instead of a critical value. The probabilistic model is adopted to describe the probabilistic relations between effective precipitation and landslide/debris flow. Correlation coefficient is calculated to evaluate the model. The result shows that effective precipitation and frequency of landslide/debris flow are normally distributed. The parameters of probabilistic model can be estimated and probability density function can be plotted. The precipitation model indicates that for each region the effective precipitation is quantitatively corresponding to the frequency of landslide/debris flow hazard. Moreover, the plotting shows that the effective precipitation increases from northwest to south east of China.