Abstract: A method for extracting harmonic response from offshore wind turbine structure, including: F1, continuously collecting its acceleration response under non-operating conditions, obtaining the acceleration response signal of the tower under only environmental load, and cropping all collected signals into signal segments with a length of L; F2, using Fourier transform to convert all signal segments from the time domain to the frequency domain, obtaining the frequency spectrum of the signal P; F3, according to the maximum rotational speed P, either designed or recorded by the SCADA system, determining the maximum harmonic response frequency Fmax=N×P, 1?N?12 to be extracted, and cropping the individual frequency spectrum into three segments P1, P2, P3, corresponding to frequency ranges of 0˜F1, F1˜F2, F2˜F3, where the selected frequency F1 is not less than Fmax; F4, cropping all frequency spectra according to F3 to form a frequency spectral dataset D without harmonic excitation effects.