Based on the absorption coefficients at 16 sampling sites in Meiliang Bay on July 17 2004, the absorption coefficients of algal particles were discriminated from those of nonalgal particles by the method of spectral criteria, and compared with those by methanol-extractions. The results were as follows. Discriminated from absorption coefficient of nonalgal particles by methanol-extractions, the absorption coefficient of alga particles shows the absorption characters of nonalgal particles when the concentration of nonalgal particles is high. The absorption coefficients of algal particles are overestimated especially in short wave band. By the method of spectral criteria, the absorption coefficients of nonalgal and algal particulates can be successfully separated. Compared with the partition by methanol-extractions,the limear correlation coefficients between absorption coefficient of algal particles at 440 nm and 675 nm and the concentration of chlorophyll a significantly increase. The limear correlation coefficients increase to 0. 8901 and 0. 8401 from 0.66 and 0. 75 at 440 and 675 nm, respectively. As far as the method of methanol-extractions is concerned,the spectral shape of absorption coefficient of particles matter significantly affects the degree of over-estima-ting the absorption coefficient of algal particles. When the spectral shape of absorption coefficient of particles matter is much more similar to that of alga particles, the error is lower； on the contrary, the error is bigger.