As is well-known, rock-fall is one of the most common geo-hazards and always causes serious damage to both lives and properties. There are many triggering factors that give rise to the occurrence of rock-fall disaster and earthquake is one of the main triggers, while often leading to a greater loss than other factors. As one of the methods to carry out researches of rock-fall, numerical simulation plays an important role in the study of movement characteristics. A conceptual rock-fall model with four cases, one without seismic loading and three with different seismic loading input modes, is used to simulate the effect of seismic loadings on the mobility characteristics by discontinuous deformation analysis (DDA). The simulation results show that the seismic loading prompts the collapse of potential rock-fall and different seismic loading input modes have different significant influences on the mobility characteristics of the collapse block. Another important conclusion is the vertical component of seismic loading has more significant influence on the movement distance of collapse block than the horizontal component, which differs from the traditional knowledge about the earthquake-induced rock-fall. Thus the vertical seismic loading should be given enough attention in the future prevention design of earthquake-induced rock-fall.