Abstract: Higher order statistics is used to extract the phase information of ship-radiated noise's periodical modulation waveforms.The results from real date analysis are compared with computer simulation and a phase extraction method is presented.The periodical modulation waveform is reconstructed from its bispectrum's phase and amplitude information,and the reconstructed signal is called'Signature'of that ship.The correlation function between three ship's signatures and their real modulation waveforms are given out.It is clear that normalized correlation between the signature and real modulation waveform of the same ship are much higher than that between different ships.One characteristic of ship-radiated noise which has a broad application prospect is discovered,ie.modulation waveform in different frequency bands of ship-radiated noise are very much alike.