Abstract: The change of the voltage quality caused by distributed generation (DG) in the micro grid is analyzed, and the voltage models of distributed generation with synchronous motor type, asynchronous motor type, and inverter type are built by considering the difference of output characteristics of DG. By taking a simple micro grid system that is simulated by PSCAD/EMTDC as example, the impacts of such factors as the change of installation location, the change of power output and disperse installation of multi DGs for above three kinds of distributed generations on the voltage quality of micro grid are studied. The simulation results show that the distributed generation with synchronous motor type and inverter type can improve the voltage quality of micro grid, while the distributed generation with asynchronous motor type has bad effect on the voltage quality of micro grid. Then the voltage quality improvement measure based the super capacitor is proposed due to the characteristic of distributed generation with asynchronous motor type reducing the voltage quality of micro grid. The results show that the proposed approach is effective and promising.