Employing the frequency hardening coefficient in the nonlinear dynamic system consisting of mobile hard disks with rubber isolator, a set of nonlinear differential equations for this system is established. The corresponding model for numerical simulation is constructed. The dynamic responses for different pulse durations and pulse magnitudes of acceleration are computed with this model. The influences of pulse signal parameters on the isolation effect are analyzed and discussed. Theoretical analysis and numerical simulation show that the model presented here is more reasonable than the traditional linear dynamic model. Furthermore, this model is simple and convenience for tation. It can be used to determine the natural frequencies of nonlinear vibration-tion system effectively.