The interfaces of geosynthetic barrier are considered to be structurally weak surfaces when the barrier is installed in the slope of landfill. However, dynamic behaviors of geosynthetic barrier under seismic excitation have not been clarified sufficiently. In the present study for the purpose to assess the seismic risk of the landfills with respect to the sliding failure along the geosynthetic barriers, the dynamic behaviors of geosynthetic barrier slope were investigated experimentally by means of shaking table tests. Firstly the dynamic behaviors of geosynthetic interfaces were investigated by sliding block experiments to evaluate dynamic friction. Secondly, the surface and global sliding failure modes of the geosynthetic barrier slope were observed depending on the thickness of bottom protection layer. Finally the stability analysis method was proposed so as to predict the failure of geosynthetic barrier slope reasonably.