By using polarization characteristics of underwater target signals

polarization characteristics of underwater target line spectrum signal is analyzed via singular value decomposition（ SVD） method in frequency domain

and the line spectrum signal is filtered by constructing polarization filtering function. The simulation and experiment results show that the polarization filtering line spectrum extraction method can extract the line spectrum signal adaptively and when the SNR of the underwater target signal is larger than-7 d B

the proposed method has high characteristic of extraction line spectrum signal.