Abstract: To solve the problem of insufficient inertia and weak frequency regulation ability caused by grid-connected new energy, an adaptive frequency regulation strategy with proton exchange membrance (PEM) electrolyzer participating in microgrid is proposed after considering their physical characteristics under high photovltaic (PV) penetration. Firstly, the dynamic model of PEM electrolyzer with double electric layers is established on the basis of the operation characteristics of the hydrogen production process. Secondly, to address the issue of light abandonment caused by reserved power reserve in PV active frequency regulation, the concept of PV-PEM electrolyzer reserve power is proposed. Then, based on the frequency deviation and frequency deviation change rate of the microgrid, an adaptive fuzzy inertia control strategy and primary frequency regulation control strategy analytical model are designed to fully explore the inertia response capability and primary frequency regulation capability of PEM electrolyzer. Finally, a coupling model of temperature control system and pressure control system of PEM electrolyzer with frequency regulation control strategy is constructed. The influence of the stable operating point position of PEM electrolyzer before participating in frequency regulation is analyzed. Simulation results verify that the implementation of the proposed control strategy for frequency regulation by the PEM electrolyzer reduces the maximum system frequency deviation by 18.63% to 25.60% compared to scenarios without frequency regulation, and a 14.76% to 16.61% reduction over conventional droop control.