Abstract: In order to improve the disturbance rejection ability of DC solid state transformer (DCSST) which is applied as the key connection device between high voltage DC distribution grid and low voltage DC microgrid, a novel control strategy based on active disturbance rejection control (ADRC) is proposed to stabilize the DC output voltage. The controller is designed based on the analysis of the DCSST circuit model, the tuning method that is dependent on gain bandwidth is given through pole assignment based on linear active disturbance rejection control (LADRC) scenario, and obtained parameters are applied to state feedback gain and state observation gain of nonlinear ADRC to achieve rapid non-overshoot response of system. Experiment results show that proposed control strategy and ADRC parameter tuning method are feasible, and the DCSST output voltage achieves faster response speed and stronger disturbance rejection ability than that of conventional PI control.