In order to give full play to the advantages of battery energy storage system and conventional units in primary frequency regulation, the control strategy of combining droop control and virtual inertia control is adopted for energy storage. The reasonable distribution of additional power between conventional units and energy is realized by setting the droop coefficient adjusted with the variation of frequency deviation. In order to avoid the phenomenon of overcharge and over-discharge of energy storage battery, an adaptive control strategy is proposed which considers the output of SOC feedback adjustment. The configuration of energy storage capacity in the power grid is not as good as that of conventional units. A control strategy is designed to timely input and exit the frequency of energy storage, so that the energy storage can be put into the frequency when the frequency changes sharply or the energy storage is out of the primary frequency range of conventional units. When the frequency is basically stable, the energy storage exits the FM steadily to maintain the SOC. Finally, Digsilent/ Power Factory software is utilized to simulate step load disturbance and continuous load disturbance of the regional power grid respectively. The results show that the control strategy can significantly improve the transient frequency characteristics under the step disturbance, and the frequency offset index and SOC can be maintained under the continuous disturbance.