Abstract: Granular avalanche happens frequently. The hazard usually causes catastrophic disasters to the manmade system along its passage. In addition, granular avalanche often provides plenty of loose sediment for debris flow, and deposits as loose packing natural dam for avalanche lake formation. A hydrodynamic model is established for granular avalanche, and a high-resolution numerical algorithm is proposed and implemented to simulate its evolution and deposit. Using the numerical model, the classical dam-break problem is at first successfully calculated. Then, the flow and deposit behavior of granular avalanche across a terrain with an obstacle is studied. Based on the results, some preliminary protection schemes for granular avalanche mitigation are discussed.