Abstract: Based on an investigation with 67 samplings from Taihu Lake in the autumn of 2004,the bio-optical properties including absorption coefficient,backscattering coefficient and irradiance reflectance just beneath the water surface,and the concentrations of the optically active substances are measured and calculated.Semi-analytical retrieval models of three optically active substances(tripton,phytoplankton pigment and CDOM) are developed using bio-optical model.Significant spatial differences are found for the concentrations of three optically active substances suggesting the spatial heterogeneous in the large shallow lake.The estimation models adequately predict tripton,phytoplankton pigment concentrations,and CDOM absorption in well-mixed and optically complex water in the Taihu Lake.