Abstract: The shock absorption capacity of composite foundation plays mainly the roles of amplitude reduction, viscous damping for energy consumption and friction energy consumption. Based on the composite foundation's shock absorption mechanism, the foundation and cushion can be simplified to be a vibrating system involving mass, damping and elasticity with multiple degrees of freedom, of which the frictional action is also taken into account. Then, a shock absorption model and dynamic equation are developed, with a program given using wilson-θ method to compute the equation. A calculating example shows that the maximum interbedded displacement due to composite foundation and cushion is much less than that due to pile foundation. In addition, the maximum value of sliding response spectrum also decreases. All these reveals that the effect of shock absorption is obvious.