Abstract: At present, there is no mature model or method for the calculation of the impact force of tailing flow discharged from the dam break of tailing pond. Instead, the empirical formula for debris flow or the existing hydraulic model are directly used, and the corresponding parameters are modified. This method can not truly reflect the impact characteristics of tailing flow. The evolution characteristics of impact force under different densities of tailing slurry, different velocities and different depths of impact are studied by using the tailing flow model groove devices. The test results show that the impact force is affected by density shadow in time distribution. The higher the density is, the earlier the maximum impact force appears. In the longitudinal space, the impact force can be divided into two parts. One is the buried depth below the liquid level, the impact force is linearly distributed with the depth, the other is the surge height part. The impact force is a logarithmic fast attenuation. The impact force of tailing flow is directly related to velocity, density and buried depth, and the velocity and impact force are power function-related under different densities. At the same time, the greater the density is, the greater the impact force is the power function related. The buried depth and impact force are linear relationship. Based on this, a model for impact force covering three factors of the velocity, density and buried depth is established, and three parameters are set up, namely, the coefficient of turbulence k₁, the coefficient of impact force adjustment α affected by the density, and the coefficient of impact force adjustment k₂ affected by the buried depth. The model can comprehensively reflect the influences of three factors. The rationality of the model and the correctness of the physical meaning of the parameters are verified, which may provide some theoretical reference for the related researches and engineering applications