Considering decentralization of the distributed generation units and loads in the microgrid and concentrating on generation types and models of the storage devices， different control strategies are used in controller design for the distributed generation units. The generation units adopting V/f control method based on the droop characteristics can facilitate load power sharing when the powers of loads vary， and can also maintain the system frequency when a unit fault occurs and the microgrid islands. And the generation units adopting PQ control method can export the referenced active and reactive power in operation. Then， the operation variations of the microgrid are respectively analyzed when it runs from grid-connected mode to islanding mode or vice versa， when it runs with load changes in islanding mode and runs with the generated power of distributed power source varied suddenly. The corresponding rules of the power， voltage and current for each distributed power source and the frequency for the microgrid are obtained. The simulation results show the correctness and validity of the PQ -V/f synthetical control scheme.