Abstract: The K492 landslide on Chengyu railway has been worsening from its first deformation in 1998. The phenomenon of road base deformation and ground crack can often be seen in rainy season. With the change of groundwater level and the water level in Yangtze River, the landslide is still in the deformation of stage. Its formation and development is mainly due to the pore water pressure in the slope. This paper determines the factors of safety associated with the landslide in different water levels. The results indicate that its instability is at the major flood level. At the same time, it is calculated the factor of safety according to the changes of water level, the development of fissures and the crack -water level. The landslide of complex water-bearing accumulation horizon should be controlled in a comprehensive way of retaining structures and drainage.