Abstract: Tanggudong landslide and Yuri accumulation body are situated at 1.5km downstream from the middle dam site of Lenggu hydropower station in the Yalong River Valley, Yajiang county, Sichuan Province. They can be a potential hazard to the safety of the planning dam. Based on local geological structure, this study establishes the inner link between Yuri accumulation characteristics and the formation process of the Tanggudong landslide. The formation process of Tanggudong landslide are found out through analysis of the Yuri accumulation body characteristics. The evolution process of the bank slope in this valley and its periodic characteristics are established. The result shows that as different individuals in the same local geological structure, Tanggudong landslide and Yuri accumulation body have some inevitable connection during the process of evolution, representing classic products of different evolutionary stages.