Abstract: The photovoltaic-storage unit based on virtual synchronous generator (VSG) control can operate in islanding and grid-connected modes. When the islanding mode is transferred to the grid-connected mode, there is a voltage and current inrush problem due to the poor traditional control accuracy. For the reason of the mutual coupling between the frequency and the phase angle, a large frequency fluctuation will occur during the pre-synchronization process. Therefore, this paper proposes an adaptive-model predictive control (A-MPC) method for the photovoltaic-storage virtual synchronous generator unit in the above-mentioned mode switching process. Since adopting a more accurate model predictive control (MPC) strategy, the frequency variation during the switching process is introduced to adjust the weighting coefficient of the MPC adaptively. The proposed A-MPC can improve the dynamic response of VSG-controlled converters in the pre-synchronization process and the mode switching process. Finally, a controller-level hardware-in-the-loop simulation experiment platform is built, and the results show that the surge voltage and current during the modes switching process can be limited when adopting the proposed control strategy.