Abstract: Since a large number of power electronics accessed to the micro-grid, which causes the lack of inertial reserves, the frequency stability issue may arise due to the fault disturbance and isolated operation. To solve this problem, the operating characteristics of the traditional synchronous machine can be simulated by adding inertia and damping in the inverter control. According to the above ideas, a virtual synchronous generator model is built based on swing equation in this paper, the dynamic characteristics of the system are analyzed, and the influence of the virtual synchronization controller with different damping coefficients on the system frequency stability is mainly studied. According to the control requirements, a variable damping coefficient control method is proposed. The simulation and hardware in-the-loop experiments have verified the correctness and feasibility of the proposed method. In the end, the traditional PQ control and the system frequency stability base on droop control are compared, which shows the superiority of proposed control method.