A static and dynamic performance testing system of fast steering mirror (FSM) is constructed. The composition of the system and testing methods are introduced. And the parts of the system are described. The sources of system errors are analyzed quantitatively. The influence of system errors can be eliminated through system design. The disturber FSM as an important part of the system is designed in detail. The layout methods of sensors and motors of the system are discussed to optimize structure design in order to make a more compact structure. The nonlinear error correction method is given to improve the control accuracy. The results show that the system can make the static and dynamic performances tests of the FSM within 70 Hz bandwidth.