The　sudden　fault　on　the　low　speed　and　heavy　duty　equipments　are　very　difficult　to　recognize　and　it　can　bring　about　great　loss.　Though　the　equipments　can　be　maintained　by　the　vibration　monitoring　technology,　the　fault　information　on　the　low　speed　shaft　can＇t　be　easily　picked　through　the　frequency　spectrum　analysis.　The　necessary　information　on　the　low　frequency　range　can　be　obtained　by　wavelet　analysis　on　the　monitoring　data.　The　sultation　coefficient　of　wavelet　decomposition　on　the　vibration　signal　in　some　time　range　can　be　regarded　as　the　characteristic　value　to　judge　the　fault.　Furthermore,　the　coefficients　can　capture　the　developing　process　of　the　fault.　For　the　same　series　monitoring　data,　the　refinable　spectrum　analysis　and　FFT　analysis　compounding　wavelet　decomposition　are　both　used　to　complete　the　comparative　research.　The　achievements　show　that　the　refinable　spectrum　method　can＇t　predict　the　fault　reason　and　location.　On　the　other　hand,　after　the　composite　signal　processing　through　wavelet　analysis　and　FFT　technique,　the　vibration　amplitudes　variation　of　the　characteristic　frequency　of　the　hidden　fault　are　very　intense.　As　a　result,　it　is　very　helpful　to　precisely　recognize　the　early　fault　on　the　low　speed　and　heavy　duty　equipments.