Abstract: The problem of process monitoring was defined by using the principle of pattem recognition.After the analysis of time-frequency character of discrete wavelet transform,a means to extract the features of frequency band in real process measurement siwgnals based on discrete wavelet transform was stru ied．Meanwhile a new pattem classification algorithm was proposed to induce the relationship of the extracted features and corresponding process conditions.The induction result was applied to process monitoring,which verified the feasibility and effectiveness of the method.