A gas chromatography-tandem mass spectrometric（GC-MS/MS） method was developed for the analysis of 20 polychlorinated biphenyls（PCBs） and polycyclic aromatic hydrocarbons（PAHs） in milk.The sample was cleaned up with Cleanert BaP SPE column.The target compounds were eluted by n hexane,and then analyzed by GC-MS/MS.The results showed that target analytes displayed good linear relationships over concentration range of 5-200 μg/L,with correlations coefficients more than 0.99.The quantitation limits were all 1.0 μg/kg.The average recoveries of 20 compounds at three spiked levels of 1.0,2.0,5.0 μg/kg ranged from 67.3% to 106.9%,with relative standard deviations（RSD） of 3.1%-13.9%.With the advantages of simplicity,rapidness and accuracy,the method is applicable for the determination of PCBs and PAHs in milk,and provides a guarantee for quality control and safety evaluation of milk.