Abstract: Active disturbance rejection control (ADRC) inherits the advantage of being based on error feedback of PID control. It does not need model prior knowledge in control, and combines the advantages of classical regulation theory and modern control theory, so it has wide applications in practical engineering. In this paper, the problems of slow dynamic response and weak disturbance rejection in traditional PID control of electromechanical actuator are analyzed; the mathematical model of the actuator system based on direct torque control is established; a linear extended state observer is designed and a simple method for determining the parameters of the observer is given, the disturbance observed by the observer compensates the system as a series integrator; different controllers are used to analyze the stability of the compensated system. According to the stability and the difficulty of realization, the proportional differential negative feedback controller is adopted. Finally, the designed observer and controller are simulated. The simulation results show that the designed observer and controller have great advantages in dynamic response and disturbance rejection compared with traditional PID control.