Abstract: The temporal and spatial distribution of petroleum hydrocarbon of surface sediment of offshore marine areas in Liaodong Bay was examined based on the concentrations retrieved from marine environmental monitoring data from 2015 to 2017. The source and degree of pollution were also analyzed and discussed. The results show that the concentration of the petroleum hydrocarbon of surface sediment in Liaodong Bay from 2015 to 2017 was in the range of 1.5×10⁻⁶~2790.0×10⁻⁶, with a median value of 62.7×10⁻⁶. The total median values of petroleum hydrocarbon of surface sediment of marine functional zones in Liaodong Bay (the top three) were:port shipping area>reserve area> agricultural and fishery areas while the sequence of total over standard rate of petroleum hydrocarbon in sediment stations of marine functional zones in Liaodong Bay (the top four) was industrial and urban sea area> reserve area>agricultural and fishery areas> port shipping area from 2015 to 2017. The results indicate that the petroleum hydrocarbon mainly comes from areas with more frequent production activities, such as port and maritime areas, coastal areas for industrial and urban use, reservation areas, agricultural and fishery areas, etc.