A double-sided slope with high water content in sandy clay was considered under the action of seismic load. Its failure mode and dynamic response were investigated using a hydraulic servo shaking table test. The typical characteristic of failure mode and dynamic responses of the double-sided slope were analyzed. Experimental results show that slope failure undergoes a process of progressive deformation. The slope failure mode can be explained as creep sliding landslide. AFA (Amplification Factor of Acceleration) at the surface and inner parts of the slope shows an increasing trend with the increase of relative elevation. The relationship between AFA and EAA (Excitation Amplitude of Acceleration) is nonlinear. An empirical formula is proposed to describe preferably the relationship between AFA, relative elevation and dimensionless EAA. The AFA at the middle and upper parts of the slope increases apparently with increasing EFA (Excitation Frequency of Acceleration).