Abstract: Aiming at the nonlinear characteristics of high-order voltage-controlled converters, a sliding mode control method to suppress the chaos in the DCM-mode SEPIC converter is proposed. The method firstly improves the selection of state variables according to the operation mode characteristics of the DCM-mode SEPIC converter, so that the corresponding phase trajectories can enter the sliding surface in the DCM-mode, and select the corresponding sliding mode coefficient according to the existence conditions of the sliding mode function. Then, the adaptive hysteresis control is introduced. By setting the upper and lower limits of the hysteresis, the purpose of stabilizing the switching frequency is achieved. Finally, the chaos control of the system is realized. The simulation results of the method by building the Simulink model of the system show that the proposed method can make the system run stably in a single-period state even in the case of large disturbances in the system, and has the characteristics of fast dynamic response and small output ripple.