The successful application of oil analysis on the condition monitoring and fault diagnosis of mechanical equipment and the importance of the atomic emitting spectrometry(AE spectroscopy) on the fault diagnosis of mechanical equipment were introduced.The methods of analyzing the data of more than 20 elements concentration containing in the AE spectroscopy analysis of oil sample were introduced,including threshold value method,clustering method and element concentration prediction method.The main applications of AE spectroscopy were analyzed,including lubrication condition monitoring,wear fault diagnosis,identifying oil type and judging deterioration of lubricating oil,and detecting oil contamination.It is proposed that the technology of oil AE spectroscopy is ineffective to the detection of the wear particles greater than 10 μm in size and information redundancy is large,and AE spectroscopy should be combined with ferrous debris monitoring device,analytical ferrography or particle counter in usage.It is pointed out that AE spectroscopy needs to improve detecting efficiency for large wear debris.