This paper focuses on the spectral absorption characteristic of colored dissolved organic matter (CDOM) in Lake Dianshan, which is the source of Huangpu River in Shanghai.The relationships between CDOM and water quality parameters, including chlorophyll a (Chi.a), turbidity and chemical oxygen demand (COD) were investigated.Spectral absorption shapes in different bands were studied to find precise S values (absorption spectrum slope coefficient).The results show that absorption coefficients of CDOM are not high, absorption coefficients at 355 nm range from 6.95 to 10.28m^-1 and absorption coefficients in the south lake is higher than that in the north lake.Corrections of CDOM and water quality parameters are not high, which show that CDOM mainly comes from urban sewage and industry wastewater.Spectral absorption coefficients of CDOM in the bands from 300 nm to 500 nm exponentially decrease with wavelength increasing while decrease linearly after 500 nm.The S values in the bands from 300 nm to 500 nm changes from 11.7μm^-1 to 14.8μm.Absorption coefficients after 500nm decrease 0.0021m^-1 per.