Debris flow causes huge casualties and economic losses to railway construction and transportation every year, so it is of great significance to analyze the severity of debris flow to reduce the loss. For the debris flow hazards severity analysis, an integrated approach based on G1-ANP was proposed. Firstly, under the condition of the environmental risk, induced conditional risk, and vulnerability risk, the 16 index factors have been selected, for example, the degree of slope, land use type, flow accumulation, and annual mean rainfall. Then, considering the interaction among risk factors, a multi-level G1-ANP risk factor structure model has been established based on the criteria of buried capacity, impact velocity, and scouring distance (or area) of debris flow and the solution process of the model was described. Finally, the risk severity and the proportion of the various risks for each section were calculated using the weighted method. The analysis results are shown in the improved radar chart. The results show that the overall severity of debris flow in the Chengkang railway is not very high. The results can provide a reference for the management of debris flow hazards prevention and reduce the losses caused by hazards in railway operation.