Abstract: Hybrid AC/DC microgrid will be an important form of future power distribution system, and it has been grasping more and more attention. However, because of the constant power load（CPL）, the DC bus is prone to oscillation and even instability. This paper selected bidirectional DC/DC converter and bidirectional DC/AC converter as research object, deduced their DC equivalent impedance, then built converters DC cascade system impedance model, and studied the stability of cascade system by the stability criterion.Researches show that, LC filter would increase the output impedance of cascade system in low-frequency stage, and the DC voltage is likely to oscillate around the peak frequency of output impedance. So, this paper proposed a coordinative virtual impedance control for improving system stability and capability of transmission power. The proposed method regulates the output impedance of source converter and the input impedance of load converter, and it can decrease the magnitude of output impedance and increase the phase of input impedance at the same time. Finally, simulation and experiment results validate the proposed control strategy and analysis.