In a microgrid, grid-connected inverters, as the interface between the distributed power supply and grid, cannot provide inertia support for the system. The control strategy of virtual synchronous generator (VSG) based on grid-connected inverters can enhance the stability of system frequency. In order to make the frequency response that has a smaller overshoot and a shorter settling time, a self-adaptive damping control strategy based on the relationship between the damping and the maximum frequency deviation for microgrid VSG is presented. The small-signal mathematical model of VSG is established, and the range of the damping coefficient is determined. Finally, simulation experiments are carried out with MATLAB/Simulink, and the effectiveness of the proposed control strategy is verified by comparing it with various damping control methods.