The invention relates to a method for quantitatively analyzing blade component distribution on the basis of a terahertz imaging technology and belongs to the techncial field of terahertz spectroscopydetection. The method firstly establishes an equivalent dielectric function of a blade according to an effective medium model and on the basis of the characteristic that percentage composition of water, solid matters and gases in the blade as well as terahertz frequency spectrums of the water, solid maters and gases can influence a terahertz frequency spectrum of the whole blade, then the percentage composition of the water, solid matters and gases in the blade is adjusted by utilizing a random optimization algorithm to enable a difference between an equivalent dielectric spectrum of the bladeand the real dielectric spectrum to be the smallest, so that the percentage composition of the water, solid matters and gases is obtained, and the real contents of the three matters in the blade arereflected. When detection is performed by utilizing the method provided by the invention, exact values of the contents of the three components, namely the water, solid matters and gases, in the bladecan be obtained at the same time during the detection, and a visual distribution image of the three components can be provided. Compard with the traditional detection method, the method provided by the invention has the advantages of being lossless and quick and is applicable to being popularized.