The invention discloses a photovoltaic power generation system based on MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) counter-current prevention. The system comprises a storage battery, a control module, at least one photovoltaic cell panel, at least one voltage detection module and at least one MOSFET, wherein only one MOSFET is connected between each photovoltaic cell panel and the storage battery, each voltage detection module is respectively connected with the negative pole of each photovoltaic cell panel, each voltage detection module is also respectively connected with the control module, and the control module is connected with the grid electrodes of the MOSFETs and the voltage detection module. According to the invention, traditional counter-current diodes are replaced with the MOSFETs, because the internal resistance of the MOSFETs in the process of being turned on is small, and greatly lower than the internal resistance of a common diode, thereby greatly reducing the internal loss of energy in the photovoltaic power generation system, and improving the efficiency of the system.