Abstract: The surface sediments from the north Bohai Sea were analyzed for 16 US EPA priority polycyclic aromatic hydrocarbons (PAHs) using gas chromatography-mass spectrometer (GC-MS) in May and August of 2014.The temporal and spatial distributions and composition of PAHs were studied,and pollution level,main sources,potential toxicity and biological effects were discussed.The total concentration of the 16 US EPA priority PAHs in surface sediments ranged from (88.5~187.7)10-9 dry weight with a mean concentration of 125.210-9in May,and the total concentration of PAHs ranged from (99.6~199.3)10-9 with a mean concentration of 126.510-9 in August,sediments can be characterized as lowly to moderately PAHs pollution,and biological effect would occur rare.The potential toxicity of carcinogenic PAHs was low-medium level.The high concentration areas of PAHs were usually in the southwest of Liaodong Bay,and the sea area of Jinzhou Bay and Pulandian Bay.LPAHs have larger percentage than HPAHs.Isomeric ratios and principal component analysis (PCA) were used in source identification,the petroleum source and combustion source were existed in the north Bohai Sea.