Abstract:The factors influencing stability of slope under earthquake are summarized according to characteristics of seismic force. The slopes are classified into two groups and seven subgroups,and their possible failure modes under dynamic force are analyzed. At the same time,the mechanism of earthquake-induced slope instability is discussed. It is concluded that seismic inertia force and building up of excess-static pore pressure are two reasons to induce instability of slope. For different slopes,the predominant factor inducing failure will be different. Plastic flow failure is mainly induced by building up of excess-static pore pressure. Rock fall and toppling failure are mainly caused by seismic inertia force. Slide failure is induced by building up of excess-static pore pressure combined with seismic inertia force in general.