The shock characteristics of a cubic nonlinear stacking packaging system were investigated under the action of half-sine acceleration pulse. The dynamical model of the system was developed, and the numerical results of the dynamical equations were obtained. Based on the results, a new concept of combined shock response spectrum was proposed to describe the shock characteristics of cubic stacking packaging system, focusing more on the maximum of the peak response acceleration of all products at all sensitive frequency since the damage of stacking packaging system occurs when any of the products was damaged. And it’s found that the combined shock spectrum is always made up of the shock spectrum of the bottom layer at lower dimensionless pulse duration and the shock spectrum of the top layer at higher dimensionless pulse duration. Then, the effect of the peak pulse acceleration, the defined system parameter, the damping ratio of cushioning pad in addition to the number of stacking layers on the combined shock spectrum of the system was discussed. It’s shown that all of their effect are noticeable. The results lead to some insights into the design of cushioning packaging.