Abstract: A method of GC-MS for the determination of 3 chlorobenzenes (CB′s), i.e. 1,3-DCB, 1,2-DCB and 1,2,4-TCB in aquatic products was proposed. Interaction between CB′s and protein was studied by molecular fluorescence spectrometry. It was shown that strong binding effect was found between CB′s and fish serum albumin. The sample of aquatic product was pretreated with bi-aqueous phase system of acetone-K2HPO4-H2O. The DB-WAX capillary column was used for GC separation and selected ion monitoring mode was adopted in MS determination. Linear relationships between values of peak area and mass concentration of the 3 CB′s were kept in the same range of 0.5-5.0 mg·L-1. On the base of blank sample, test for recovery was made by standard addition method, values of recovery found were in the range of 77.0%-116%, with RSD′s (n=6) in the range of 2.6%-7.1%.