Aiming at the problems of long test cycle, high cost and vulnerable to bad weather in actual road test, a six-degree-of-freedom swaying platform is designed, which can be used for simulation test of vehicle-mounted electro-optical tracking system. The disturbance is provided by the six-degree-of-freedom (Dof) swaying platform. The structure design, motion and frequency characteristics analysis of the six-degree-of-freedom swaying platform are carried out. The results show that the relationship between the natural frequency and the stiffness matrix and mass matrix of the mechanism can be deduced.