Abstract: The optimum pretreatment process is especially required in order to get the exact concentration of PCBs in municipal sewage.In the paper, C₁₈ solid-phase extraction(SPE) columns were adopted in the enriching of PCBs in Harbin municipal sewage, and the target compounds were extracted with mixed extractant of acetone and n-hexane of 1:1 in the optimum dosage of 10 milliliter.And the extract was further purified with sulfuric acid, silica gel and anhydrous sodium sulfate.GC-MS was applied in the identification and quantification of PCBs in sewage samples, and seven PCBs congeners recommended by EPA were chosen as the exterior references.It indicated that the total concentration of the seven PCBs in the sewage samples was 27.75 ng/L, the relative standard deviations of the method were in the scope of 1.6%-8.8%, the recoveries were between 84% and 103%, and the lowest detection limit of PCBs was 0.014 μg/L.