Fast Steer Mirrors(FSMs) should possess different effective bandwidths and close bandwidths under different situations. So this paper establishes a system model based on a piezoelectric FSM control system, and optimizes the control strategy for the FSM system by analyzing the jitter of an optical axis. Firstly, close loop Bode figure of the system was measured, the simulated annealing algorithm was used to achieve the modulation transfer function of the system model. By combining simulated annealing algorithm and the identified model, an optimal PID controller to meet all kinds of applications was presented. Finally, the step response tests were used to verify the correctness of the identification model, and the closed-loop tests were taken to validate the effectiveness of the optimal controller. Experimental results indicate that the indentified model fits the FSM system very well in low-middle frequency stage, its step response is similar. The system controlled by the optimal controller has a closed-loop bandwidth of 70 Hz, an effective bandwidth of 35 Hz, and the tracking accuracy is improved by 47%, meeting the requirements of FSMs in the current environment. It concludes that the system has good low frequency tracking ability and high frequency interference rejection ability, showing high tracking precision and low device loss.