Abstract: As the penetration of the distributed energy source in the grid is becoming higher and higher,new control techniques are needed which allow the distributed energy source actively taking part in the power regulation of the power system. The virtual synchronous generator（VSGs）, as one of the alternative solutions, has drawn much attention. This paper proposed a line-frequency-averaged small signal model of the VSG. Based on the model, it is further demonstrated that the coupling effect between the active power loop and the reactive power loop can be ignored under certain conditions, thus the control parameters of each loop can be designed independently. In order to guarantee the stability, dynamic performances and the ability to attenuate pulsating power of the system, the design method for the control parameters of the VSG was also proposed in this paper. The experimental results were given to verify the effectiveness of the theoretical analysis presented above.