Bispectrum and slice bispectrum analysis techniques, which are excellen t in nonGaussian and nonlinear signal processing, were employed to analyze the vibration signals of a centrifugal pump under different running conditions. The results show that the bispectrum of the vibration signals have remarkably differ ent features under the conditions of normal running, ground bolt loosening and c avitation. So, it can be used to classify the fault signals. By using the anti d iagonal slice attributes of bispectrum, the noise is suppressed markedly and the characteristic frequencies is well extracted. The examples of fault diagnosis i ndicate that the bispectrum and the slice bispectrum are effective in fault diag nosis of centrifugal pumps.