To overcome the limit on the natural resonant frequency and bandwidth of the traditional single-axis servo system, the paper designed a double-axis compound servo system, and established the transfer function of the fast reflector, camera, D/A data acquisition card and velocity servo unit, and further obtained the transfer function and theory model of this servo system. By combining simulation, it analyzed the influence of the dynamic hysteresis error, flat vibration error, centroid detection error, mechanical torque distortion error on the accuracy of the system. It proposes the view that the modern synthesize algorithm can optimize and compensate the parameter of the fast reflector system, by this method designed robust controller can restrain the remaining low frequency distortion and high frequency noise of the system, and further improve the bandwidth and accuracy of the system. The experiment shows that the compound-axis servo system bandwidth is of 2-16Hz and system accuracy of 0.8-4μrad.The experimental results and theory analysis are compatible basically. The design provides a foundation for the study on the servo system in the fields of the space optical communication system, deep space detection, remote sensing and etc