The invention relates to an inverse beamforming method. The method comprises the following steps: discrete fourier transform is performed on a received signal to obtain a frequency domain value of the signal; a cross-spectral matrix is calculated for receiving a towed line array according to the frequency domain value; correction is performed on main diagonal elements of the cross-spectral matrix; Toeplitz averaging is performed on the corrected cross-spectral matrix to convert the corrected cross-spectral matrix into one-dimensional distribution data having the spatial distribution characteristic; phase compensation is performed on the one-dimensional distribution data in the theta angle, and then the summing process is performed to obtain a power spectrum in the theta angle; spatial scanning is performed on the power spectrum in the range from 0 degree to 179 degrees to obtain a spatial spectrum P'(f) at the current signal frequency f; and P is made to be equal to the sum of P and P'(f), and f is made to be equal to f+1, and when f is less than or equal to fmax, the above steps are repeated, or else the operation is finished, so that the broadband inverse beamforming process is completed.