Abstract: The ability of a fast-steering mirror (FSM) to track a target accurately and steadily depends on its servo control performance. The larger the aperture of the FSM is, the more difficult it is to design the flexible supporting hinge and the driver; in addition, it will also demand greater requirements on the servo control. To solve this problem, this paper proposes a fuzzy adaptive tune(FAT) proportional integral derivative (PID) control algorithm, which not only uses fuzzy theory for adaptively tuning the control parameters, but also inherits the classic PID controller for engineering realization. In this study, we designed a controller for the ϕ500 mm FSM driven by a voice coil motor, conducted simulation experiments, and compared the results with the simulation results based on classic PID control. According to the results, the overshoot was 5.4%, the settling time was 51.0 ms based on FAT PID control, and the capacity of resisting disturbance was stronger than that of the classical PID control. In addition, compared with traditional PID control, the proposed control method improved the ϕ500 mm FSM response speed, decreased the tracking error, and improved ϕ500 mm FSM system tracking performance and robustness.