In order to improve the trajectory tracking accuracy of electrohydraulic servo system, a continuous sliding mode controller was designed for trajectory tracking control of electrohydraulic servo system. In the modeling process of the electrohydraulic servo system, the voltage and current equations of the solenoid coil were obtained based on the displacement of the control valve core. Under the action of the hydraulic fluid, the flow equation of the hydraulic fluid in the cylinder was established. According to the trajectory error of the system, the sliding surface model was constructed. Based on the openloop transfer function state space model, the continuous equation of the control law was established, and then the continuous sliding mode controller was obtained to overcome the uncertainty and disturbance of the electrohydraulic servo system, so that the calibration trajectory could be accurately tracked. Compared with the tracking results of the disturbance observer, when using this method to tracking arc and square wave calibration trajectory, the tracking accuracy is improved by 31.23% and 39.98% respectively. This method can effectively improve the trajectory tracking accuracy of the electrohydraulic servo system.