Abstract: In order to solve the problems of small inertia and weak frequency stability of power electronic microgrid, this paper used virtual synchronous generator (VSG) control technology to improve the stability of microgrid. VSG can simulate the inertia and damping characteristics of the traditional synchronous generator and provide inertia and damping support for the system. Therefore, this paper first established a microgrid model with virtual synchronous generators, then studied the effect of VSG's virtual inertia and virtual damping on frequency stability, and a method of virtual inertia and virtual damping parameters optimal design for frequency stability was proposed to improve the frequency stability of the system. Finally, a three-machine nine-node virtual synchronized microgrid system was used as an example to verify the effectiveness of this method.