Abstract: As a kind of emerging organic pollutants, perfluoroalkyl substances(PFASs) have attracted much attention of researchers.In the present study, 17 kinds of PFASs in surface seawater samples from Dalian bay were measured with high performance liquid chromatography tandem mass spectrometry detector(HPLC-MS/MS) combined with solid-phase extraction pretreatment.Furthermore, the pollution level and distribution of PFASs were analyzed.PFASs were detected at all sites, indicating that PFASs were still ubiquitous in Dalian bay, and the total concentrations of PFASs ranged from 8.1 to 13.8 ng/L.Among them, perfluoronoctanoic acid (PFOA), perfluorobutanoic acid (PFBA) and perfluorobutane sulfonate (PFBS), are predominant PFASs pollutants in surface water samples from Dalian bay.Short-chain substances are gradually becoming the predominant PFASs pollutants, which needs more attention in the future.As for the pollution distribution, the concentrations of PFASs inside the Dalian bay are higher than those outside the bay due to the influence of the dilution and diffusion of seawater.However, the concentrations of PFASs at the west of Sanshan Island are relatively high and the potential pollution sources remain to be further studied.