Scattering coefficient bp, backscattering coefficient bbp and concentration of particles are obtained from Taihu lake waters during three campaigns in Oct. 2006, Mar. 2007 and Nor. 2007. Specific scattering and backscattering coefficient of total suspended particle (TSPM), inorganic suspended partide (ISPM) and organic suspend particle matter (OSPM), and spectral power exponents slope are calculated from sampling data. Then the spectral characteristic and formative mechanism of bp and bbp are explored further. The result indicates that the average value of specific scattering coefficients of TSPM, ISPM and OSPM are 0.634 (550 nm), 1.057 (532 nm) and 0.396 (532 nm) gm-2, respectively. The average value of specific backscattering coefficients of ISPM and OSPM is 0.0051(532 nm) and 0.0022 (532 nm) gm-2. The average backscattering ratio(B) in Oct. 2006, Mar. 2007 and Nov. 2007 is 0.01078, 0.01375 and 0.01251, respectively. bbp, bp and B have strong wavelength dependence. However, strong absorption effects of OSPM and CDOM at short wavelength and chlorophyll at 675 nm make the wavelength dependence weak. Spectral exponent has strong relation with ISPM/OSPM, bbp(532 nm), but week relation with the particle size distribution slope.