For the impact of a large number of intermittent distributed power connecting to micro-grid, this paper proposes a new extension of demand response definition and takes frequency control into the area of demand response. Meanwhile, demand response is divided into user demand response and grid demand response. The impact of grid demand response on stabilizing intermittent power and its significant role in improving the micro-grid stability are analyzed. It analyzes that taking charging stations of electric vehicle as a main controllable load of demand response has more realistic feasibility than as a distributed generation. A more economic operational control strategy which regards the electric vehicle charging station as a grid demand response object is proposed and the micro-grid model is built on Matlab/Simulink simulation platform. By simulation comparison, in the micro-grid islanding operation, it verifies that this control strategy has excellent performance of FM and good stability when it faces large fluctuations of micro grid.