Parallel factor analysis and known fluorophores were used to characterize and identify the components of CDOM,and the dynamics of CDOM was analyzed further based on the Three-Dimensional Excitation Emission Matrix Fluorescence Spectroscopy (3DEEM) of CDOM measured on Nov. 2008 in lake Taihu. Humic-like matter was the mainly fluorophores of CDOM. The source of Protein-like maybe the debris of aquatic organism. The emit wavelength of Humic-like moved to the long wavelength with the in- crease of fluorescence intensity, namely, the "Red Shift" effect. The 3DEEM can be decomposed to six primary components by the parallel factor analysis, and six components can explain 92.48% variation, and the average contribution of six primary components to 3DEEM were 19.7090/(PC1),18. 685%(PC2),16. 914(PC3),16. 62%(PC4),l5. 514%(PC5)and 12.5580/(PC6),respectively. The value of abso lion shoulder in the 275nm was mainly affected by peak N,following peak M. The main influencing factors of its shape was peak A and N, then peak T and M. The source of CDOM can be divided into Four styles accord-ing to the tluorophores types; terrestrial dominate style, leaning-terrestrial dominate style, leaning-autochthonous dominate style and autochthonous dominate style.