Abstract: To improve the control effect of the automatic voltage regulator system, a model-free sliding mode controller (SMC) based on a high-order differentiator (HOD) is developed. The traditional SMC is combined with the HOD. The controller does not involve the specific parameters of the system and can effectively use the HOD to accurately estimate the state information of the system during the control process. After successfully achieving effective control of the Duffing chaotic system, the model-free SMC is employed to control the AVR system. The results are compared with those obtained using HODFC, PID particle swarm optimization, and PID chaotic ant colony optimization. The simulation results show that the proposed model-free SMC has a low overshoot, high tracking accuracy, robustness, and strong suppression of noise interference.