On the basis of analyzing the process of the traditional droop control system to adjust the active power and frequency, two improvement strategies of micro-grid operating in grid connected and isolated mode are proposed. Using the improved control strategy, micro-grid can operate at the rated frequency after reaching steady state in isolated mode; Inverter based source can supply active power according to the preset of the active power value automatically in grid connected mode, and for energy storage device, it will convert to absorb active power from the grid, for adjustable micro source, it can supply a rated active power. Simulation results validate the effectiveness of the proposed strategy.