As one of mountain hazards,sand-sliding hazard usually endangers severely transportation,industrial and agricultural production and our life and property because the frequency of their occurrences is high.Mohr-Coulomb criterion and energy conservation law were applied to deduce the sliding critical condition and rolling condition of single sand.The restitution coefficient was applied to describe the impact problem.The research findings may help to understand the formative mechanism of sand-sliding hazard and control of sand-sliding hazard.