At the lake ecosystem, the CDOM (colored dissolved organic matter) not only is an important source of nutrients, but also is major component of carbon cycle. Based on the fieldworks of water qualities experiments at Taihu lake, China, on 27 and 28 October, 2003, the present paper used the Landsat/TM imageries to study and estimate the distribution pattern of CDOM concentration at Taihu lake. According to the study results, it was found that CDOM was a strong absorber at TM1 band, where there was a wave trough at that corresponding wavelength. Taking the reflectance at TM1 as a remote sensing parameter, the remote sensing technology could perfectly retrieval the CDOM concentration from the Landsat/TM imagery at TM1 band. Compared with the validation dataset at two stations, the mean bias between modeled prediction and in situ measurements was 0.922 mg·L-1, and the corresponding relative bias was 14.85%. Additionally, the retrieval results show that the spatial distribution of CDOM concentration was higher in the south and center of the lake, but lower in the east and west lake.