Microcystis aentgino.su and Scenedesmus obliquus, which were the main part of algal community in Lake Taihu,were studied in this paper. Under the definite conditions of light and temperature circumstance, they were cultivated. Then their absorption and scattering coefficients were measured by AC-S(Wetlabs Inc).M. uentginosu and S. obliquus had simi-lar absorption spectra characteristics, but the phyc:oerythrin and phycocyanin's absorption positions between M. uentginoso and S. obliquus are different obviously. Package effect and the effect of absorption on scattering of M. oentgino.sa,which has relatively small size,was smaller than that of S. obliquus, which has relatively big size, however, the linear and power slope of P-L absorption model of M. uentginosa was bigger than that of S. obliquus. Variable factors of scattering optical model had some differences because of different effect absorption on scattering. Variable factors of M. aentginosu and S. obliquu.s scat-tering model wereλ₀/λ, and a（λ₀）/a（λ）,respectively. Both M. uentgirzoso and S. obliquus scattering models were suit for international common form of S-P model.