Fast-steering Mirror (FSM) with its precise positioning characteristics and fast response ability, occupies an increasingly important position in the field of space science and communications. FSM is one of the top technologies at present[1]. At present, analog galvanometer control system imported from abroad is mainly used in the domestic market, which has the disadvantages of weak anti-interference ability and difficult to expand[4]. Based on this, a high-speed, 90mm digital FSM control scheme is designed in this paper. The working principle of the system is analyzed, the software and hardware design of the system are described, and the position sampling principle and control method of FSM are introduced in detail. Using digital notch filter to suppress mechanical resonance, a digital FSM control system based on DSP is developed. The experimental results show that the control bandwidth of the system reaches 300 HZ, and the system runs stably and reliably, so it has great application prospects[2]. © 2019 IEEE.