In order to predict the impact of tailings dam break on the downstream, an improved DB-IWHR model based on the modified Shields curve was established by modifying the calculation of critical shear stress. Through the example of Tangjiashan barrier dam, the higher accuracy of dam break and discharge process evolution of the improved DB-IWHR model was verified. A numerical analysis model for the impact of a tailings dam break was established by using the improved DB-IWHR model and a two-dimensional hydrodynamic model. The submerged range, depth and arrival time of dam break on the downstream were obtained, and the impact of the tailings dam break on the downstream key sensitive points was predicted.The sensitivity of the improved model to the initial width of the breach and erosion parameters was analyzed. The results show that the improved DB-IWHR model, combined with the two-dimensional hydrodynamic model, can better simulate the dam break process of tailings pond and the evolution process of sediment discharge flow. The results conform to the general law of sediment flow movement. The model is not sensitive to the initial breach width, but it is sensitive to erosion parameters. Keywords: tailings pond; dam-break influence; DB-IWHR model;critical shear stress; two-dimensional hydrodynamic model 〖FL