The characteristics of typical AE signals initiated by mechanical component damages are analyzed. Based on the extracting principle of acoustic emission(AE) signals from damaged components, the paper introduces Wigner highorder spectra to the field of feature extraction and fault diagnosis of AE signals. Some main performances of Wigner binary spectra, Wigner triple spectra and WignerVille distribution (WVD) are discussed, including of timefrequency resolution, energy accumulation, reduction of crossing items and noise elimination. Wigner triple spectra is employed to the fault diagnosis of rolling bearings with AE techniques. The fault features reading from experimental data analysis are clear, accurate and intuitionistic. The validity and accuracy of Wigner highorder spectra methods proposed agree quite well with simulation results. Simulation and research results indicate that wigner highorder spectra is quite useful for condition monitoring and fault diagnosis in conjunction with AE technique, and has very important research and application values in feature extraction and faults diagnosis based on AE signals due to mechanical component damages.