Abstract: Taking a practical project for example，the three dimensional numerical model of dam break is set up to make numerical simulation on the evolution law of debris flow from dam break and obtain the submerged area and the law of velocity and accumulation depth varied with time.Then，the experimental data verified the numerical simulation results.Applying the landslide and diversion dam to the practical engineering aimed at artificially changing the evolution direction of debris flow to maximumly reduce the damage.By analyzing the protection effect of the landslide and diversion dam to the debris flow，it is verified that the landslide and diversion dam could not only guide the debris flow，but also retain parts of debris flow.Therefore，it can effectively reduce the evolution distance of debris flow to the downstream.

Key words: Tailing pond, Dam break, Debris flow, Landslide and diversion dam