Abstract:Rock and soil are existing in the nature with strong spatial variation and regionality. The regional property of slide zone clay is one of important reasons that some characters of landslide failure are similar in the Three Gorges reservoir area. According to characteristics of slide zone clay,the Three Gorges reservoir area is divided into three parts:from dam site to Miaohe,from Miaohe to Fengjie except Zigui basin,from Fengjie to Chongqing and Zigui basin,where 391 groups of shear strength data of slide zone clay have been collected. Probability distribution of shear strength parameters of each part is determined by statistics;and these distributions are the prior ones. Based on these distributions,the shear strength parameters of slide zone clay of neogenic landslide can be presumed by Bayes estimation. For landslide with a few test values,the shear strength parameters can be optimized by Bayes estimation;and for neogenic landslide without test values,the shear strength parameters of slide zone clay can be obtained with some data of neighbouring and similar landslides by Bayes estimation. The method has been proved by Qianjiangping landslide(2.4×107 m3),a typical neogenic landslide in the Three Gorges reservoir area. The method that shear strength parameters of slide zone clay are gained by Bayes estimation is important to prevent and control neogenic landslide in the Three Gorges reservoir area.