To analyze the transformation of tailings dam outburst into debris flow, a physical model test and numerical simulation method were studied based on the physical model experiment. Based on Voellmy model and similarity theory, the runout of the flow material of the failure tailing dam was analyzed in this paper. The physical modeling similar to the prototype was applied to analyzed the flow distance, flow velocity and deposit depth at first, then a flume test was used to determine the dry friction coefficient and the viscous coefficient of the flow material, and the numerical simulation based on Voellmy model and motion RAMMS software was developed to verify the physical simulation results. The results show that in the process of tailing dam failure, the higher the saturation lines are, the greater the sliding distances are. The degree of dam failure was related to the dry friction coefficients and viscous coefficients of flow material. Under these experimental conditions, the flow distance, flow velocity and deposition depth were similarity between the physical modeling and numerical simulation. The comprehensive application of this method can provide a reference for the accurate prediction of the range of the rainfall induced tailing dam failure disaster damage.