Abstract: The features of the ship noises which were recoded by us before are analyzed by the higher-order spectrum after the study of their distribution in this paper. The results show that the different ship noise has different scope of the main frequency. The main frequencies of the first class ships are less than 120 Hi, while the second between 130~320 Hz. The different relationships between ω₁ and ω₂ correspond to different bispectrum graph. There are the same results in the trispectrum. The feature vector is consist of the ω₁ which correspond to the maximum bispectrum B (ω₁,ω₁) and the maximum trispectrum B (ω₁,ω₁, ω₁) respectively and the ω₁ and ω₂ which correspolld to the maximum bispectrum B (ω₁, ω₂).