A landslide with volume of 130104m3 occurred at Fuling Fifth Middle School in Chongqing on Jan 3，2008. It is a bedding monoclinic rock landslide. This paper presents the investigation on the characteristics and causes of the landslide. The paper summarizes the findings. At firstly，the inclined terrace and cracked rock mass were the structural factors causing the landslide. Secondly, because they were softened in water and acted by tectonic stress in geologic history, the argillaceous sandstone and mudstone were prone to argillation and forming weak seams. The weak seams comprised montmorillonite and illite. The weak seams were the controlling factor causing the landslide. Thirdly, water weakened the strength of the weak seam. Finally, digging slope toe was one of the inducing factors to the landslide. With creeping of the landslide, the factors acted each other and led to the occurrence of the landslide.