Abstract: In Yanqing Competition Area of Winter Olympic Games Beijing 2022,the snow making and water diversion project is an important supporting project,which is responsible for water storage and water supply in the competition area. Due to engineering functions and topography conditions,the engineering site area is a favorable geological environment for debris flow disaster,and the main hydraulic facilities are faced with high risk of debris flow. At present,it is difficult to use debris flow dynamic numerical simulation method to simulate and predict sediment erosion thickness under multiple rainfall conditions. In terms of this issue,we propose two indexes: the mean thickness of water yield in debris flow gully and the mean thickness of stone produced by source under different rainfall recurrence periods. And we simulate and predicte the potential debris flow disaster in engineering area with UAV measurement,remote sensing interpretation,field investigation and Massflow. The results show that hydraulic facilities(damp and pumping stations) at different elevations face different debris flow threats,under different rainfall recurrence periods. The debris flow risk of 1050 dam is the highest,facing the double damage of siltation and alluvial,followed by the debris flow risk of 900 pumping station and 1290 reservoir. The former is mainly siltation damage,the latter is mainly alluvial damage. The risk of debris flow is low at pump station 900 and pump station 1050. Based on simulation analysis and field investigation,it is suggested to build a sand dam upstream of 1050 reservoir,a diversion channel on the east side of 1290 reservoir,and a sand settling basin at the end of 900 reservoir to ensure long-term safety operation of hydraulic facilities.