Aiming at the problem of the low signal-to-noise ratio（ SNR） of underwater target line spectrum signal

underwater target line spectrum detection method based on Gammatone auditory filter bank is proposed. Because the cochlear has good the characteristics of frequency division and sharp filtering

the Gammatone auditory filter bank is used to divide the line spectrum signal to different channels

at the same time

according to the feature that the phase of line spectrum signal changes more relatively steady than that of noise spectrum in each channel

the frequency spectrum of each channel is weighted by the standard deviation of phase

and the detection performance of the method is given. The simulation and shore-based laser interferometer experimental results showed that the proposed method can detect the line spectrum signal at low SNR. The detection probability showed that it is 1 when SNR is-7 d B

which is higher than that of the conventional fast Fourier transform（ FFT）. The proposed method provides a new way to detect and distinguish line spectrum signal.