Abstract: For a spacecraft recovery system, its electronic devices may experience a high-level random vibration during the launch time, therefore, the design of a vibration isolator is necessary. Firstly, the dynamic model of the system of the avionics and the damper is established, and the method for measuring the stiffness and the damping characteristics of the damper is proposed. Then, a wire rope damper with internally-filled polyurethane rods is designed, and its stiffness and damping characteristics are measured by the sweeping frequency experiment, to estimate the vibration damping performance of the dynamic model. Finally, the random vibration test of the damper system is carried out under the flight environmental conditions. It is shown that the prediction of the damper system’s performance is in good agreement with the testing result. The method can be used to help the design of similar damping systems in future tasks.