The effects of liquefaction on cyclic deformation of soil layers are investigated by shaking table tests. Taken the dry sand tests as a consult, the relations between the pore water pressure increasing and the accelerations and deformation of the soil layer are presented. The results show that the liquefaction greatly reduces the acceleration amplitude and inertia force of surface ground, meanwhile however, the cyclic deformations of the soil layer increase significantly. The cyclic shear strain in liquefied soil layers can reach 1 %-5% and the strain in the upper layer is less than that in the sub layer. The sensitive range for obvious change of the cyclic deformation appears when the water pressure ratio is about in 0.4-0.8 and reaches the maximum when is about 0.8 rather than 1.0. As a result, the liquefied soil layer reduces the vibration of the rigid superstructure, but the increasing cyclic deformation due to liquefaction can easily destroy the foundation and underground structures, especially for the part of the foundation and underground structures near the interface between the liquefied layer and non-liquefied soil layer.