Abstract: In the traditional control strategy of virtual synchronous generator (VSG), the rotational inertia and damping coefficient of synchronous generator (SG) were introduced, which solved the problem of lack of inertia in large-scale distributed energy access to microgrid. But the fixed rotational inertia cannot take account of the power oscillation and frequency fluctuation under load disturbance. Aim at this problem, a control strategy with adaptive rotary inertia based on secondary frequency was proposed in this paper, which could enhance the system inertia and realize real-time dynamic adjust of power and frequency. Firstly, the mathematical model of VSG was established with reference to the external characteristics of SG, analyzed the influence of different rotational inertia on the dynamic response of the system in island mode. Secondary, adaptive inertia control was formed by feeding back deviation value and change rate of angular frequency to the rotational inertia. This strategy could reduce the overshoot and oscillation time of the system under load disturbance, analysis of the influence of main control parameters on system stability. Finally, through Matlab/Simulink simulation software, compared to the traditional VSG control strategy, it was proved the presented method to be feasibility and superiority.