In the past 20 years laser scanning technology has been widely used in the field of industrial processing. As a more efficient laser control instrument 3D scanning galvanometer mainly relies on foreign imports for its core components and key technologies. In view of the fact that there are few domestic studies on the 3D scanning galvanometer system and under the traditional control method the galvanometer motors generally have problems such as slow step response and low control accuracy so a discrete sliding mode controller based on the combination of a novel reaching law and a disturbance compensator was designed. This control method effectively compensates for external disturbances and has strong robustness.Firstly a linear dynamic model of the voice coil motor based on the 3D scanning galvanometer system was established and the model was discretized to construct its discrete state space equation secondly the discrete system controller was designed according to the sliding mode variable structure control theory finally the simulation model of the control system was built through Simulink. The simulation results show that the step response times of 1% and 10% of the full stroke were 2. 1 ms and 2. 4 ms respectively and the positioning accuracy of the 10% full-stroke sinusoidal signal position tracking was within 3×10-4 mm. It can completely track the command signal meet the requirements of engineering application and provide a new idea for the control research of high-speed three-dimensional scanning galvanometer system.