The large-scale integration of new energy sources into islanded microgrids through inverters has led to a continuous decrease in the system inertia level, and the system frequency is facing severe instability risks. In response to this issue, this paper proposes a frequency active support control method for new energy inverters based on virtual inertia fuzzy adaptive control, which utilizes the DC side capacitors of new energy inverters to actively support system frequency. Firstly, by introducing a power control term based on fuzzy control in the control loop of the new energy inverter, which couples the DC side capacitor voltage of the new energy inverter with the system frequency, the DC side capacitor has an inertia response similar to that of a synchronous generator. Then, considering the differential demand for virtual inertia in the frequency response process, a fuzzy control rule is designed to adaptively adjust the additional virtual inertia of the DC capacitor of the new energy inverter according to the frequency fluctuation interval, in order to slow down the system frequency offset speed, improve the system frequency extremum, and accelerate the system frequency recovery speed. Subsequently, the stability of the system after adopting the proposed control method is proved by constructing Lyapunov function. Finally, the effectiveness of the proposed control method is verified through simulation and experiments.