Abstract: Deqin County is one of the areas suffering the most serious geological disasters in Yunnan Province. Based on the development characteristics of the debris flow in the Zhixi River, this study identifies five disaster-generating modes for the debris flow in the Zhixi River: Collapse - clastic flow, rock landslide-clastic flow, soil-rock mixture landslide-clastic flow, loose accumulation layer -bedrock contact surface landslide-clastic flow and landslide in loose accumulation layer-clastic flow. The FLO-2D model is used to simulate the debris flow movement in the Zhixi River under the rainstorm cycle of 10, 20, 50 and 100 years, and the maximum flow velocity, the maximum accumulation depth, the accumulation distance and the volume scale in different rainfall return periods are quantitatively analyzed. The results show that the debris flow is characterized by high acceleration, fast velocity, strong destructive force, and long circulation area when it erupts. When the debris flow occurs once in 100 years, its maximum velocity reaches 3.07 m/s, the maximum mud depth is 2.27 m , the volume of debris flow washed out is 84419 m³, and the disaster area reaches 91600 m². The results provide quantitative data reference for the prevention and control of debris flow disasters in Zhixi River, and also provides an important basis for the design of disaster prevention and mitigation projects in Deqin County.