Changing the inertia coefficient in the Virtual Synchronous Generator (VSG) control strategy will cause system instability. Thus a hybrid energy storage-based control strategy without changing the inertia coefficient is proposed. First, the load or new energy fluctuation is regarded as the additional quantity of VSG rated power after passing through the first-order high pass filter as with a conventional VSG control strategy. Secondly, the battery connected to the DC terminal of the VSG is used to provide droop power, and the super capacitor provides virtual inertial power and additional inertial power. This improves the frequency dynamic characteristics of the microgrid. Then, the output coefficient related to the state of charge of the supercapacitor and the additional inertial power is introduced to realize the adaptive control of the supercapacitor and optimize the state of charge of the supercapacitor in the inertia strengthening process. Finally, an islanded microgrid with VSG as the inverter control interface is built in Matlab/Simulink. The effectiveness of the proposed strategy is verified by simulation under different loads, light intensities and supercapacitor states of charge. This work is supported by the National Key Research and Development Program of China (No. 2018YFB0905304).