Abstract: The microgrid changes from grid connected mode to off grid mode. The traditional control methods of energy storage converter and photovoltaic inverter may cause the problems of microgrid system oscillation and overcharge and discharge of energy storage system. The microgrid structure with energy storage converter and photovoltaic inverter running in parallel is adopted. By analyzing the output power of each power supply of microgrid, a method is proposed when microgrid is off grid. Considering the variable master-slave cooperative control strategy of the charged state of the energy storage system, that is, the advantages of master-slave control, peer-to-peer control and hierarchical control are combined to complete the flexible switching of the energy storage converter between the droop control and PQ control of secondary voltage and frequency regulation, realize smooth off grid of microgrid, and prevent overcharge and over discharge of the energy storage system. Finally, a simulation model is built to verify the effectiveness of the proposed method.