Abstract: The blocking effect during debris flow movement is an important topic in in the study of debris flow prevention. In this study, the concept of erosion rate is introduced, established a continuous model of debris flow including blocking dam, and clarified the effect of the dam on debris flow movement behavior and dynamic process. The results show that the planned mitigation works would suffer tremendous impact caused by the accelerating debris. The blocking dams perform the dual function of intercepting and blocking, the blocking dam plays a dual role of interception and blocking, which makes the lateral extension of the debris flow disaster body enhanced, the vertical extension weakened, and the slip distance reduced, reducing the debris flow disaster scope. On the other hand, it reduces the erosion entrainment effect of debris flow, reduces the mass of disaster body, and decreases the area and volume of disaster body by 2.48% and 3.63% respectively; meanwhile, it deviates the flow direction, decreases the average velocity of mudflow movement by 10.62%, alleviates the impact force of debris flow, reduces the disaster energy of disaster body by 16.17%, and further decreases the disaster intensity and scale. The numerical model introduced by basement topography and erosion rates provides theoretical support for debris flow dynamics mechanisms and technical guidance for debris flow prevention.