The invention provides a high-frequency isolation single-phase photovoltaic grid-connected system and a control method thereof. The high-frequency isolation single-phase photovoltaic grid-connected system consists of a photovoltaic array, a buffering capacitor, a high-frequency converter, a high-frequency transformer, an AC / AC converter, a filter and an electric power grid. A high-frequency chain-linked technology is utilized, so the electrical isolation between a photovoltaic power generation system and the electric power grid can be realized, the isolation transformer and the weight and the size of the entire system are reduced, only two-level power conversion is required, the topology is simplified, and the reliability of the entire system and the electric power transformation efficiency are improved. In addition, aiming at the characteristics of the topology and the photovoltaic system, an optimized control algorithm is proposed, so the unfavorable influence of the system from the fluctuation of the voltage outputted by the photovoltaic array can be overcome, the high quality of the electric power outputted by the entire system can be ensured, the distortions is small, the dynamic reaction is fast, the energy can flow in two directions, and reactive compensation can be supplied according to the requirement of the electric power grid.