The invention provides a global optimization method for control parameters of a photovoltaic power generation system. The method comprises the following steps: firstly, an established differential-algebraic equation of a photovoltaic plant power generation system is linearized at a steady-state value to obtain a state matrix used for analyzing the small disturbance stability of the system; then the influence on the system small disturbance stability of the system caused by control parameters is analyzed by calculating the eigenvalue, the damping ratio and participation factors of the state matrix to further determine the reasonable variation range of the control parameters; and finally, a quantitative model is introduced to serve as a parameter optimization objective function and the optimization algorithm is utilized to achieve global optimization of the control parameters of the photovoltaic plant power generation system. According to the invention, as for the small disturbance stability of the system, a scientific and reasonable quantification standard is established, and the problem of difficult single optimization due to mutual coupling of the system control parameters is solved. By adopting the method for parameter optimization, global optimization of the control parameters can be realized, and the small disturbance stability of the photovoltaic plant power generation system is improved.