The wavelet packet transform is a new multi-scale analysis method developed in the past decade.It overcomes the shortcomings of poor resolution in high-frequency part inherent in wavelet analysis.Vibration fault feature of gear is analyzed.By using the decomposition and reconstruction algorithm of wavelet transform

the fault feature signal of gear are extracted availably and the result s of experimentation are obtained.The characteristics of time domain analysis

frequency spectrum analysis and wavelet analysis are compared

and the predominance of wavelet energy spectrum analysis in extraction and diagnosis of fault signal is proved.