The performance of excitation control system directly influences the motor’s movement characteristics. Currently, a lot of traditional excitation systems which use analog control circuits have the problem with their poor stability, aging components, slow response and great power lose. Aim to solve these problems, this text designs and implements a digital excitation regulation system based on DSP for DC motor. The regulation system takes full advantage of the powerful data processing ability of DSP chip for real-time rotational speed control of DC motor. This design is capable of ensuring the stability of the excitation system and improving the control efficiency, the circuit design is greatly simplified at the same time.