Abstract: From investigations after earthquakes,it can be found that strong earthquakes generate serious geological disasters in mountainous ranges.Due to topography,the ground motion acceleration of some regions are greatly amplified,even some large stones are thrown into the air with high speed.In the light of seismic wave propogation,this paper analyzes the reflection stack of seismic waves from different treflection angles and different reflecting interfaces,and gives a preliminary explanation for the mechanism of that amplification.The main conclusions are as follows: (1)The topography is the main reason leading to amplification effect of the ground motion; (2)Amplification effet is closely related to mountain slopes; (3) Mountain strikes cause differences in horizontal components.Based upon that,some suggestions are proposed for the earthquake disaster prevention in mountainous regions.