Abstract: Variations of spectral characteristics for dissolved organic matter(DOM)were studied by analyzing the three dimensional fluorescence excitation-emission matrix(3DEEM)spectra, and then the effect of external glucose on the emission and transformation of DOM was investigated. Samples of the sediment from Erhai lake was cultured by adding four concentrations of glucose solution (0,0, 100and 200mg/L for C₁,C₂, C_3and C_4treatments respectively). The result of this study revealed:①there existed six forms of fluorophores, which represented protein-like fluorescence substance and class fulvic acid respectively. Phenomena of “blue shift” and “red shift” ocurred when fluorescence peak positions were on 1-8d and 8-17d, respectively. ②The luorescence intensities of fulvic acid in the ranges of ultraviolet and visible light increased with the progress of culturing. The peak A appeared as C₄1, while the peak M occurred as C₄>C₁during the initial cultivation, but opposite during the late cultivating period. ③With the extension of the cultural progress, protein-like fluorescence presented “the single-peak” curve changes in the overlying water. The “peak” appeared after eight days. During the entire cultivation period, protein-like fluorescence presented as C₄>C₁. The addition of glucose promoted biological transformation of DOM in the sediments of Erhai Lake, and a part of DOM those are difficult used by microorganisms transformed into protein-like substances.