Abstract: In order to enhance the stability of the grid system connected to the new energy, the virtual synchronous generator technology is introduced, and the purpose is to virtualize the grid-connected inverter into a synchronous generator. The basic equation of the virtual synchronous generator includes active and reactive power control, that is, the control of the system frequency and voltage is realized through these two parts, wherein the moment of inertia of the active control loop of the synchronous generator and the inertia coefficient of the reactive power control loop have a great influence on its stability, and the small signal model of the power loop is established by analysis, the influence of moment of inertia and the coefficient of inertia on the stability of the system is analyzed, and the basis for the selection of parameters is provided, and the parameter value that can make the system more stable is finally selected.