Abstract: In the viewpoint of seismic engineering,the horizontal seismic force is the decisive factor that leads to rocksoil mass destruction,while the vertical seismic forces are negligible. In view of huge destruction of the slopes and constructions caused by vertical seismic force in Wenchuan Earthquake,this paper conducted a numerical simulation research on the horizontal and vertical response law of the vertical acceleration in the slope with different heights and slope angle under the influence of the Pwave with different cycles and amplitude by use of FLAC finite difference software. The results showed that when the slope height is low,the acceleration,less than half of the slope height,increases with the height,while more than half of the slope height,it remains unchanged. When the slope height increases,the acceleration changes with a regularity,and the acceleration in the peak of the slope is bigger than any other parts in the slope. The bigger the slope angle and the greater the vibration acceleration enlargement ranges.The vibration acceleration increases as the amplitude increases. They have significant linear relations.The vibration acceleration on the slope increases as the cycle gradually decreases. 