In order to study fluorescence characteristics of typic azo and non-azo dyes, fluorescence characteristics of acid orange Ⅱ, indigo carmine and acid orange Ⅱ without azo-bone are detected by excitation-emission matrix (EEM) fluorescence spectra. Results show that fluorescence intensity of typic azo dyes (such as acid orange Ⅱ) is very weak, while fluorescence intensity of typic non-azo dyes (such as indigo carmine) is very strong. In other words, azo dyes in wastewater can be distinguished quickly by EEM spectral technique. It is clear that azo-bone of azo dyes has fluorescen quenching, which results in deep depression of fluorescence intensity for azo dyes (such as acid orange Ⅱ). When azo-bone of azo dyes is broken down by electro-fenton, their fluorescence intensity increases dramatically, and this phenomenon is the unique features of azo dyes.