Increasing penetration of renewable energy decreases the inertial level of power systems. The virtual inertia control of energy storage systems and renewable power generations effectively deals with the low inertia problem. With the increasingly perfect inertia market, it is significant for grid operators to optimize the virtual inertia cost. Therefore, this paper proposes a fuzzy virtual iner-tia control method, which dynamically adjusts the virtual inertia with the variation of the frequency deviation and the rate of change of frequency. Furthermore, in addition to the reduction of the inertia cost, the proposed method could also improve the performance of frequency regulation. Finally, the simulation results are analyzed to demonstrate the effectiveness of the proposed control method.