To acquire the depth profile of suspended particle scattering coefficient and the mechanism of surface reflection, three different depths of Taihu Lake scattering coefficient and backscattering coefficient are obtained in Nov. 2008, respectively. And their characteristic variation with depth is studied. Profiling distribution of the slope of particulate size distribution (PSD) is computed by the attenuation coefficient. Profiling distribution of the concentration and composition of suspended particle is computed according the relationship between the scattering coefficient and the suspended particle concentration. Impact dominant factors on scattering coefficient of the depth of water are divided according to the range of refractive index. At the three depths (0, 50, 100 cm), the particle scattering, with the percentage 14%, 17%, 12% of the samples are dominated by algae, respectively. 35%, 30%, 34% of the samples are dominated by inorganic particulate matter and Non-algal organic particulate matter,and 51%, 53%, 51% of the samples are dominated by the above all. The results can be concluded as: scattering and backscattering coefficient of Taihu Lake water body changes with depth slightly. The concentration of total suspended particles is of more diversity in different lake area, but there is less difference at different depths except those samples near the inflow rivers. The main factors of scattering coefficient of most aquatic scattering in Taihu Lake had little difference at different depths, except several samples beside the inflow rivers.