The spatial-temporal distribution, source, and potential ecological risk of polycyclic aromatic hydrocarbons (PAHs) in surface seawater from Laizhou Bay were investigated. The total PAHs (ΣPAHs) concentration ranged from 277 to 4393 ng/L with an average of 1178 ng/L, thereby suggested a relatively moderate to high PAHs exposure level in Laizhou Bay in comparison to other bays in the world. The composition patterns and source apportionment results revealed that the coal, biomass burning, diesel emissions and petroleum combustion as well as the combination of these processes were the dominant sources of PAHs in the surface water, which were closely associated with sail process and sewage effluents. The ecological risk assessment indicated that BaP, Phe, Flua and Nap would exist ecological risks in most of surface seawater sites, but the Probabilistic risk assessment (PRA) results showed that the current level of risk is not as severe as the Risk quotient (RQ) results revealed.