Abstract: In order to satisfy the high precision demand of photoelectric tracking system, a servo system was designed for a novel fast-steering mirror in detail. Firstly, the mathematic model of fast-steering mirror was established. A method of combination of velocity closed loop and position closed loop was adopted for the servo system of fast-steering mirror, and the parameters of the position compensation and the velocity compensation were designed. Secondly, the servo system was realized based on DSP. And the constitution of the servo system was expatiated clearly. Thirdly, the two working modes and the software working process of the servo system of fast-steering system were all described. Finally, the fixing point experiment and the tracking experiment were finished to verify the performance of the servo system of fast-steering system. Experimental results indicate that the response of the fast-steering servo system is very fast, the stable error of which is less than 0.3in the fixing point experiment. And the mean square root of the tracking error of the fast-steering servo system is less than 7in the tracking experiment. The servo system for the novel fast-steering mirror can satisfy the system requirements of high precision and fast response for the photoelectric tracking system.