Serious seismic damage is expected owing to the occurrence of lateral displacement following soil liquefaction after a strong earthquake. Currently, there is a need for increased research on the lateral deformation occurring inside a liquefied foundation and its spatial distribution characteristics. Considering the initial geostatic stress of a slightly sloping site, a finite-element model that reflects the liquefaction-induced slippage of the liquefiable site with a slightly inclined ground was designed. According to the results, the steeper the ground slope is, the weaker the soil liquefaction in the slope body will be. As the ground inclination and the intensity of input ground motion vary, the lateral slippage of the liquefiable soil layer transforms from the liquefaction-induced slipping along a single sliding surface to that along multiple sliding surfaces. The dominant lateral displacement of liquefiable soil layers in the slope body changes as well, from liquefaction-induced slippage of soil to largely large single-direction accumulated shear deformation of softening soil, as a result of the drastically reduced intensity of the liquefiable soil. In addition, a similar linear relationship is found among the maximum lateral displacement, the ground settlement near the slope crest, and the ground uplift near the slope foot.