Abstract: Stability of the accumulation body at Xiazanri is very important to the establishments of the Liyuan hydropower station on the Jinsha River. This station is to be built. . Based on field reconnaissance material of the Xiazanri accumulation body, the paper studies its formation mechanism and stability. The results show that it is a complex accumulation body which comprises moraine, alluvium, lake sediment and colluvium and has gone through 2 ice ages, i.e., the Jinjiang ice age in middle pleistocene and the Lijiang ice age in middle Pleistocene. The results of stability assessment show the Xiazanri accumulation body is stable as a whole despite it can have some partial fallings. The key factors controlling whether it will be stable or instable are the stabilities of the loose gravel layer at the slope toe and the lake sediments.