Abstract: In order to compensate for the negative impedance characteristics of constant power load in the direct current (DC) microgrid, it is necessary to speed up the response speed of the hybrid energy storage system and give full play to its performance. This paper proposed a linear active disturbance rejection control parameter tuning method based on the mixed potential function theory for the energy storage converter of the microgrid. Firstly, the active disturbance rejection transfer function of the energy storage converter was derived. Then, the stability of the DC microgrid with a hybrid energy storage system and constant power load was analyzed, and the mixed potential function criterion considering the bandwidth ω₀ of the extended state observer was derived, which provided an important basis for tuning the linear extended state observer bandwidth and the state error feedback control parameter of the energy storage converter with active disturbance rejection control. Experimental results show that the proposed method has a fast response speed and strong disturbance rejection ability, which ensures the stable operation of the DC microgrid system.