The invention discloses a parameter identification method for a grid-connected photovoltaic power generation system based on transient disturbance. The grid-connected photovoltaic power generation system comprises a photovoltaic array, a DC/DC converter, an inverter controlled by a VSC, an inverter, an inverter controller, and a filter circuit. The filter circuit is connected with a power grid. The DC/DC converter is connected with a maximum power controller. The inverter is connected with the inverter controller. The method is based on an improved genetic algorithm-particle swarm optimization(GA-PSO). By analyzing current changes under different transient disturbances, optimal identification of inverter parameters is achieved. The problem that a traditional mathematical analysis method is inaccurate in identification of the inverter parameters is solved, and a foundation is provided for research on inverter control optimization, low voltage ride-through, power grid power flow optimization and the like.