In this paper the mechanical structure and the operating principle of a fast steering mirror (FSM) are introduced, and a novel FSM based on magnetostrictive actuators is designed. The modal analysis of the FSM is carried out with the help of the finite element method, and relative experiments are also conducted. The experimental results and that of simulation are given and in good qualitative agreement with each other. This paper pays attention to ameliorating the FSM structure for higher mechanical natural frequency and perfect control performance. The experimental results would be helpful for the construction design of the FSM.