Based on the investigation of the water body of the drainage system of Water Diversion from Yangtze River to LakeTaihu, the absorbance spectrum and fluorescent characteristics of chromophoric dissolved organic matter(CDOM) and its sourcewere analyzed. The correlation between CDOM and some water quality indexes including pH,DO and chlorophyll-a concentrationswas discussed. The results showed that CDOM concentrations were positively correlated with their absorption coefficients at 355nmwith significantly spatial differences. S values also indicated that Wangyu River was affected by terrestrial input much more thanother areas. Five fluorophores were observed by three dimensional excitation emission matrix (3DEEM) fluorescence spectroscopyincluding UVC protein-like, UVB protein-like, UVA humic-like, UVB humic-like, and UVC humic-like fluorescent signals. Thefluorescence intensities of protein-like fractions(especially peak T) were much stronger than those of humic-like fractions. BothpH and DO concentrations exponentially decreased with CDOM concentrations. According to the correlation between chlorophyll-aconcentrations and CDOM concentrations, humic-like fluorescent signal might transformed by microorganisms. Fluorescence indexhad a value of about 1.9,therefore, CDOM could be dominated mainly by local microbial sources, and terrestrial input could bealso a source of CDOM for part of the rivers.