Electrically excited linear synchronous motor (EELSM) maglev control system can realize direct drive and frictionless feed, effectively improving the steady state and dynamic performance of servo system. Considering the uncertainty disturbance of EELSM system, the active disturbance rejection control (ADRC) strategy is proposed. According to the special structure and working mechanism of EELSM, the mathematical model of EELSM system is derived, including the voltage equation, magnetic levitation force equation and motion equation of the excitation circuit. The third-order nonlinear active disturbance rejection control (NLADRC) is designed. Taking the outside disturbances above the maglev system as total disturbance, the total disturbance is estimated and compensated, and the system anti-interference ability and the tracking accuracy can be effectively improved. Considering that the NLADRC has multiple parameters tuning and the physical meaning is not clear, the law of the nonlinear function parameters tuning is summarized. Finally, the simulation model of the ADRC system is established. The simulation results show that the EELSM servo system with ADRC has good dynamic performance and can effectively suppress disturbance in comparison with PI controller.