Three-dimensional fluorescence spectrum (3D-EEMs) and principal component analysis (PCA) were used. The three-dimensional fluorescence spectrum of urban sewage was divided into four spectral regions: aromatic proteins, microbial metabolites, humic acids and fulvic acids. Determine the regional principal component contribution rate of the lambda λ. Calculate the value of the first principal component area of each area, to establish it with water chemical oxygen demand (COD) and total nitrogen (TN), studies the urban sewage treatment effect rapid analysis and evaluation method.The results show that the urban sewage fluorescent material is mainly composed of aromaticity protein material, microbial metabolites, humic acid and fulvic acid material, regional fluorescent distribution is different, the material in the process of sewage treatment aromaticity protein material area spectral changes obviously, and the microorganism metabolites humic acid and fulvic acid material area spectral changes smaller, Spectral regions the value of the first principal component area and water body has a good correlation between COD and TN, aromaticity of protein material spectrum coefficient of the value of the first principal component areas related to the COD reached 97.63%, aromaticity protein material and the sum of the value of the first principal component area microbial metabolites and humic acid and fulvic acid material ratio of the sum of the value of the first principal component area (Yp/Yf) and TN correlation coefficient reached 94.02%.By combining the three-dimensional fluorescence spectrum of water with the principal component analysis method, the dimensionless extraction of fluorescence spectrum information of each process of sewage treatment is realized, the overlapping of fluorescence peaks and redundancy of spectral information of each substance are avoided. Through the spectral characteristics of each substance in the water, the spectrum is divided into different material regions, the first principal component region value of each region is obtained, which improves the accuracy of substance identification and effectively solves the problem of spectral information identification of each substance. By using the correlation analysis of the first principal component area value of aromatic protein spectrum and Yp/Yf and the conventional water quality indexes COD and TN, it provides a real-time and effective method for monitoring the quality of domestic sewage and solves the problem that the sewage treatment process is difficult to accurately monitor in real-time. Therefore, the three-dimensional fluorescence spectrum combined with principal component analysis method can be used for fast discrimination of urban domestic sewage treatment process, providing a new fast on-line monitoring and analysis method for water quality monitoring, process optimization and treatment effect evaluation in the sewage treatment process.