Polychlorinated biphenyls (PCBs) are a class of chlorinated organicchemicals,have polluted every place on Earth,and living creatures are alsoaffected.PCBs contamination of sea mammals,such as porpoises and whales,and seabirds is very serious since they have very high concentrations of PCBsaccumulated in their bodies.PCBs is a high fat soluble chemical substances,and not easy bebiodergradable,so easy to accumulate cumulatively through the food chain inbiology.PCBs have been demonstrated to cause a variety of adverse healtheffects,including effects on the endocrine system and other health effects.Studies in humans provide supportive evidence for potential carcinogenic andnon-carcinogenic effects of PCBs.The toxicity associated with PCBs and itsdetrimental health effects was recognized.Commission Regulation(EC) No1881/2006 setting maximum levels for Dioxin-Iike PCBs in foodstuffs.《Foodcontamination limit 》 of china ( GB 2762-2005) setting maximum levels for PCBsin aquatic products.The MRL-maximum residue limit for PCBs was suggestedto be less than 2 mg/kg in Marine fish and shellfish,shrimp and algae food.The conventional Gel permeation chromatography as a sample purificationtechnology can effectively remove the matrix grease pigment from thesample,generally uses the offline method.With troublesome operation,longtime sample processing,big solvent consumption and limits its wideapplication in many fields.In the present investigation,a on-line gel permeation chromatography-gaschromatography/mass spectrometry (GPC-GC/MS) method were developedand well validated to determine 7 polycblorobiphenyls (PCBs) in sea-fish.The PCBs residues were extracted with acetone and n-hexane underultrasonic operation,and the extract was first cleaned up with an Silica gelsolid phase extraction column and then separated and detected with theon-line GPC-GC/MS system.This method showed good linearity within therange of 0.001~1.0μg/mL.The recoveries of the method ranged from 81.6% to118.6%.The limits of detection were ranged from 0.02 to 0.09 μg/ kg.Theseresults showed that online GPC has a great capacity to remove matrixinterferences and improve the method trueness and precision.GPC/GCMSmethods are feasible to determine PCBs in aquatic products.