Identifying elution region of each constituent is important in multi-component chromatographic analysis. A new method, called evolving subwindow comparison (ESC) method, based on difference among spectra of different constituents, is proposed to identify the elution region. By incorporating the prior information of spectra, the elution region of certain component can be identified from elution region graph directly and expediently. Furthermore, such method is little affected by minor embedded interferent. On the other hand, the ESC method can be employed to diagnose the elution pattern of constituents of our interest. The method is also helpful to resolve two-way chromatographic data. The performance of the method is demonstrated on simulated HPLC-DAD data and real traditional Chinese medicine (TCM) GC-MS data.