In order to investigate the influence of debris flow in the Reshui river gully on the Yanjiang expressway and residents in the basin, the formation conditions of debris flow were analyzed by means of field investigation, data statistics and quantitative prediction, and their main characteristics were discussed. The quantitative comprehensive evaluation and classification of debris flow susceptibility were carried out, and its development trend was predicted. The results show that the terrain of Reshui river basin is steep, the branch gully is developed, the source is rich, and the rainfall is concentrated, which is generally conducive to the breeding of debris flow disasters. The debris flow is a rainstorm gully debris flow, which is prone to occur. It is currently in the development period(mature period), and the risk of recurrence in the future is high, so comprehensive measures should be taken to prevent and control it.