To improve the servo bandwidth of fast steering mirrors with large stroke, a fast steering mirror with linear driving mode was proposed. Voice coil actuators were used to drive the fast steering mirror, and ball splines were used to constrain the direction of the drive, which transforms the traditional arc drive into a linear drive. First, the structure of a fast steering mirror driven by linearity was designed. Subsequently, the composition and characteristics of linear driving were analyzed. Subsequently, after the influence of the factors of the driving forms on the servo bandwidth was analyzed considering the constraint condition, the dynamic equations of the fast steering mirror with large stroke in the two driving modes were obtained. Finally, the mechanical resonance frequencies of the fast steering mirror were obtained through finite element analysis, and its servo bandwidths were verified through experimental tests. The experimental results indicate that, under the same experimental conditions, compared with the traditional arc drive, the resonant frequency of the fast steering mirror increases from 121.8 Hz to 229.9 Hz, and the servo bandwidth increases from 40.3 Hz to 75.1 Hz, indicating an increase of 88.8% and 86.4%, respectively. These results satisfy the design requirement of high servo bandwidth for fast steering mirrors in large stroke state.