Abstract: We use modern control and mechanical dynamics to study a double mass-spring damping system. We es-tablish the state space model and the simulation structure of the damping system in accordance with its physical laws because they reflect approximately the relationships among and changes in state variables and reveal its internal characteristics. The state space model can recognize the internal characteristics of the damping system and therefore is applied to determining its controllability and observability. Besides, we use the modal superposition method to study quantitatively the dynamic performance of the damping system. Then we give the lower natural frequency, mode of vibration and displacement response of the damping system under harmonic excitation.