Two-degree-of-freedom nonlinear packaging system model was established. The shock dynamic equations were obtained and their numerical solutions were solved by the forth order Runge-Kutta integration method. The shock response characteristics of hyperbolic tangent packaging system with critical component were investigated. Final peak saw tooth shock pulse was chosen as excitation in the computer simulation and three-dimensional shock spectra of critical components were obtained. The influences of frequency ratio, amplitude of pulse excitation, package material damp, and shock period on shock response of critical components were discussed. The results showed that frequency ratio, amplitude of pulse excitation, package material damp, and shock period all have significant influence on the peak value of shock response of critical components.