To solve the problems of the contradiction between response speed and overshoot and the poor anti-interference ability in the complex electromagnetic environment, the traditional PI controller is used in the resonant magnetic perturbations (RMP) coil power supply in tokamak. This paper adopts the linear active disturbance rejection control strategy to extract the differential quality of the reference signal in the transition differentiator to achieve fast current output without overshoot. Based on partially known mathematical model parameters of the power system, a fourth-order linear extended state observer is designed to estimate the disturbance of the system as a new state quantity to compensate the internal uncertainties and external disturbances of the power system. Finally, the simulation results show that compared with the traditional PI control strategy, the active disturbance rejection control strategy can effectively improve the dynamic characteristics of the output current signal. At the same time, it has stronger robustness and anti-interference characteristics in the case of complex environmental disturbance.