A "cW (pollutant concentration in water) Balance Method" was proposed, and the kinetic parameters for bioconcentration of No. 0 diesel water-accommodated fraction by phytoplankton was measured and calculated by a modified bioconcentration model with non-linear fitting software. The data and parameters obtained by "cW Balance Method" showed well correlationship with those by the extraction of ultrasonication bath with the equilibrium method. The technique proposed in the present study is particularly well suited for the study on the bioconcentration of organic pollution toxins in the field for its convenience, simplicity, veracity and reliability.