Aiming at the problem of insufficient primary frequency regulation resources of power grid in the future, an adaptive control strategy based on charging and discharging margin is proposed for virtual energy storage of electric vehicle aggregation to participate in primary frequency regulation of power grid. Firstly, regulatory and operating range of the electric vehicle is analyzed. Secondly, the primary frequency regulation method of electric vehicle aggregation participating in the power grid is studied. Considering the margin of charging and discharging time and state of charge (SOC), charging and discharging margin index of electric vehicles is designed. Then, an adaptive primary frequency regulation control strategy based on charging and discharging margin is proposed to optimize the droop power of electric vehicles participating in primary frequency regulation, which considers both requirements of primary frequency regulation of power grid and charging, discharging of electric vehicles. Then, the primary frequency regulation capability of virtual energy storage in electric vehicle aggregation is evaluated by regular update, and the evaluation index of primary frequency regulation effect is proposed. Finally, through the simulation analysis of regional power grid cases, the effectiveness of the proposed strategy in reducing the system frequency deviation and optimizing the primary frequency regulation output of electric vehicles is verified.