Stable supply of electrical energy on the low-voltage load side of a DC microgrid is an important guarantee for the effective consumption of new energy in the new power system. To solve the problem of unstable output of the microgrid energy supply hub converter when there is disturbance, an improved active disturbance rejection (ADR) strategy for observer state variable reconstruction compensation is proposed. First, by analyzing the unavoidable structural problems in the ADR framework, an accurate paradigm of observation error is derived, and the disturbance observation variables are reconstructed and compensated to achieve fast tracking and elimination of the total disturbance. Then, the correctness and effectiveness of the improved strategy are verified by theoretical analysis of the four dimensions of stability, tracking, anti-interference and robustness performance. Finally, actual working conditions simulated by digital simulation and physical experiments are used for comparative analysis. These verify that the strategy has good dynamic performance when there is a variety of internal and external uncertain disturbances in the microgrid system.