Abstract: In order to investigate the pollution level of heavy metals in surface sediments in the northern part of Hailing island, the surface sediments were collected from 11 sites in November 2017. The concentrations of heavy metals (Hg, Cu, Pb, Zn, and Cd) in sediments and the sediment particle size were systematically tested. We evaluated the pollution level of sediment heavy metals using the potential ecological risk index and the geo-accumulation index. Qualitative assessment of the influence of sediment particle size on the distribution characteristics of heavy metals and tracking the possible sources of heavy metals were also conducted. The synthetical results showed that heavy metals except Hg had a higher concentration in the nearshore or estuarine areas than that in the central sea area. The particle size of sediment showed a fine-coarse-fine trend from west to east. Comparing with the national marine sediment quality, almost all heavy metal concentrations of surface sediment in different sampling sites did not exceed the Class Ⅰ standard. The range of potential ecological risk index (RI) was 168.6～747.5, and the average of the RI was 322.47. It means that the heavy metals in the sediments of Hailing island sea area had a great potential to influence the environmental and ecology conditions. The rank of mean value of the geo-accumulation index (Igeo) was: Hg (2.09) >Cu (0.70) >Zn (0.38) >Pb (−1.01) >Cd (−1.40) , indicating that the heavy metals except Hg manifested in a level of light pollution. The relatively heavy pollution areas concentrated in the nearshore areas, indicating that human activities were responsible for the heavy metal pollution. The correlation analysis between heavy metals and sediment grain size showed that a negative correlation existed between heavy metals concentration and sediment particle size, indicating that the smaller the particle size, the stronger enrichment ability of heavy metals. In addition, the correlation and clustering analysis between heavy metals indicated that Cu, Cd and Pb may be accumulated due to the river input, while Zn and Pb could be derived from human activities in Hailing island, and Hg may come from human-made pollution sources in the southeastern part of the bay.