The shock characteristics of cubic nonlinear stacked packaging system with critical components 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. Then, to evaluate the damage potential of shock to the critical components of the system, a concept of combined shock response spectrum was proposed.Based on the results,the effect of peak pulse acceleration,mass ratio, frequency ratio, damping ratio of critical component and cushioning pad in addition to the number of layers on the combined shock response spectrum of the system was discussed.