The invention provides a method for constructing a wind power plant frequency domain equivalent model. The wind speed at a certain point in a wind power plant space is used as an input quantity, the total active power of a wind power plant is used as an output quantity, the overall frequency domain equivalent model of the wind power plant is built, the model is divided into a positive wind speed channel and a negative wind speed channel, the positive wind speed channel represents and meters the energy transformational relation of the wind power plant after time-lag, wake flow, a tower shadow, wind shear and other space influence factors, and the negative wind speed channel represents the total cut-down function of each wind power generation set pitch angle controller in the wind power plant on excess wind power. The method avoids the difficulty of accurately building the models of the time-slag, the wake flow, the tower shadow, the wind shear and other space influence factors of the wind power plant in a time domain, and the influence of various space influence factors and the wind power generation set pitch angle controllers on the wind power plant energy transformation function is accurately metered in the equivalent model obtained through measured data in a frequency spectrum mode.