Fast wavelet multi-resolution analysis (wavelet MRk)provides a effective tool for analyzing and canceling disturbing components in original signal. Because of its exponential frequency axis, this method isn’t suitable for extracting harmonic components. The modified exponential time-frequency distribution(MED)overcomes the problems of Wigner distribution(WD), can suppress cross-terms and cancel noise further more. MED provides high resolution in both time and frequency domains, so it can make out weak period impulse components from signal with mighty harmonic components. According to the time behavior, together with frequency behavior in one figure, the essential structure of a signal is revealed clearly. According to the analysis of algorithm and fault diagnosis example, the joint of wavelet MRA and MED is a powerful tool for fault diagnosis.