In order to solve the problem of voltage stability of DC distribution network bus, a variable gain linear extended state observer (VGLESO) is designed, which effectively solves the problem of peak output of the traditional high gain linear extended state observer (LESO) in the initial stage of operation. Based on this, a variable gain sliding mode active disturbance rejection control (ADRC) strategy is proposed, which is applied to the voltage outer loop of AC-DC bidirectional converter control system in DC distribution network. The variable gain sliding mode active disturbance rejection control strategy can track and compensate the total disturbance of the system without adding additional current transformer, effectively restrain the voltage fluctuation of the bus and improve the dynamic response of the system. The stability of VGLESO and variable gain sliding mode ADRC is proved theoretically. Finally, the feasibility and correctness of the control strategy are verified by MATLAB /Simulink.