Abstract: Bailong River Basin is one of the most developed and serious areas of debris flow disaster chain in China. In order to support and serve the disaster prevention and mitigation of the large geological chain in Bailong River Basin, the debris flow in Zhaizigou, Zhouqu County, Gansu Province, was selected as the research object. Through on-site survey and mapping, combined with multi-period remote sensing data, laboratory test and numerical simulation results, the development characteristics, formation conditions and evolution model of debris flow were discussed in depth. Finally, the paper puts forward some suggestions on preventing the risk of debris flow disaster chain.The results show that: Zhaizigou is a gully type debris flow, the longitudinal slope of the gully bed is 324.5‰, and the high level source amount is 2129.23×10⁴ m³. The key disaster landform of Zhaizigou is unique, the necessary disaster formation and disaster control structure are complex, and the important triggering conditions are obvious, which has all the conditions for the occurrence of a huge debris flow disaster chain. The evolution model of the disaster chain is the disaster chain of high level collapse-barrier body collapse-debris flow, barrier lake and outburst flood. On this basis, it is proposed that the risk prevention and control of the disaster chain of the huge mudflow in Bailong River basin should focus on strengthening the disaster chain investigation and identification ability, tackling the key disaster chain monitoring, early warning, forecasting and risk prevention and control technology, and strengthening the disaster chain project disaster prevention and reduction and emergency disposal capacity. Finally, according to the characteristics and key problems of different risk areas from the perspective of river basin, the risk prevention and control model of Zhaizigou debris flow disaster chain risk prevention and control is constructed, which can provide reference for the disaster prevention and reduction of similar massive debris flow disaster chain in western mountainous areas.