The vulnerability assessment of diversion dike was studied in order to provide an effective method for the determination of the rank of prevention and control engineering and the assessment of disaster prevention and mitigation capability of diversion. By taking Queer Gully diversion dike of Yalu Road suffered debris flow disaster as engineering background, referring to previous research results on vulnerability, the concept of vulnerability of diversion dike has been proposed in this paper. According to the characteristics of debris flow to cause disaster and the characteristics of the diversion dike bearing the disaster, the engineering vulnerability evaluation method of diversion dike suffering from debris flow is established, and the combination hierarchy method is used to solve the problem of index weight. The established evaluation method is applied to assess the diversion dike of Queer Gully and the result is highly vulnerable, which shows that the overall operation of the project in the study area is poor and the protection ability is weak. It is necessary to take measures in time to ensure its normal service. The evaluation results are consistent with the field investigation and quantitative calculation results, which verifies the feasibility of the method.