Abstract: The feature Chromophoric dissolved organic matter(CDOM) and its source in Meiliang bay and Da Taihu lake in Taihu Lake are analysed based on every 2 time's samplings in summer with algal bloom and winter.CDOM absorption coefficients and chlorophyll a concentration are significant higher in summer than winter.The DOC concentration and the CDOM absorption coefficients a(355) are in the range of 5.17-12.42 mg/L,2.57-6.77 m^-1,respectively,with the maxima at the mouth of Zhihu river on Dec.15.Significant positive correlations are generally found within a(355),DOC concentration and normalized fluorescence F_n(355).The determination coefficients between a(355),DOC concentrations and F_n(355) are significantly lower in summer than winter due to the phytoplankton degradation.As the parameters representing the CDOM composition and the source,the DOC-specific absorption coefficients a^*(355) are remarkably larger in summer than winter.However,M and S values are smaller in summer than winter with the seasonal variations.The spatial distribution of the CDOM absorption coefficients is similar to that of chlorophyll-a concentration in summer with algal bloom.A significant and positive correlation is found between a(355) and chlorophyll-a concentration,which shows that phytoplankton degradation is one of the potentially important sources of CDOM.By contrast,no significant correlation is found between a(355) and chlorophyll a concentration in winter.The CDOM absorption coefficient generally decreases from the mouth of river to the inlet and outlet of Meiliang bay,which shows that river terrestrial input is the potentially main source of CDOM.