Damping design is important for keeping the performance and reliability of airborne inertial navigation system. Under the environment of the airborne inertial navigation system, the requirement of damping system is presented in this paper, and the relevant dynamic model is set up according to the platform inertial navigation system and the strap-down inertial navigation system. The damping design of airborne inertial navigation system is presented, which includes choosing the structure of damping system, determining the material and structure of damper and the inherent frequency of damping system. According to the design method, a damping design of platform inertial navigation system is put forward and satisfied by the demands of this damping system.