Due to the potential impact of standalone photovoltaic (PV) systems during grid integration, they may impose disturbances on the power grid and face challenges in autonomously perceiving and tracking grid frequency changes during operation, leading to suboptimal frequency characteristics and reduced operational reliability. This paper proposes a photovoltaic pre-synchronization and autonomous tracking control strategy based on Virtual Synchronous Generator (VSG) technology. Initially, a VSG-based control model for photovoltaic pre-synchronization during grid integration is established. Subsequently, VSG active-frequency and reactive-voltage controllers based on droop control are designed. Finally, a PV-VSG autonomous control simulation model is constructed to validate the pre-synchronization characteristics of standalone photovoltaics and the responsive tracking features of grid-connected photovoltaics to system frequency changes. The results indicate that the proposed control strategy effectively achieves pre-synchronization with the system, promptly connecting when required by the grid, and promptly sensing and following grid frequency variations, showcasing its capability to adapt to grid frequency changes in a timely manner.