Abstract: Water sample (250 mL) was extracted with n-hexane (30 mL), and the extract was evaporated and made up to 1 mL. VB quartz capillary chromatographic column (30.0 m×0.25 mm,0.25 μm) was used for separation in the temperature range from 110 ℃ to 210 ℃ with programmed temperature elevation. ECD was used in the determination. Values of detection limits of 11 polychlorinated biphenyls were found in the range of 0.01-0.02 mg·L-1. Using blank water sample as matrix, test for recovery was made by standard addition method, giving recovery in the range of 83.5%-96.4% with RSD′s (n=10) less than 11%. The proposed method was applied to the determination of polychlorinated biphenyls in water samples from 6 sampling points of Poyang Lake, giving values of average results of 1.79 ng·L-1 in high-water season and 2.34 ng·L-1 in low-water season.