A total of 49 surface sediment samples from Southern Hainan Island were analyzed for heavy metals and grain size in order to identify their possible sources and assess their potential ecological risk. It showed that the surface sediments consist mainly of sand and silt and with scarce gravel and clay. The mean concentrations of the selected heavy metals were relatively low from the southern Hainan Island and the highest reached 38.98 mg/kg of Zn. Except for As, the other elements(Zn, Cu, Cd, Pb, Cr and Hg) exhibit significant positive correlations with each other and the contents of silt and clay. The assessment result of ecological risk revealed the southern Hainan Island possessed light potential ecological risks with the mean RI value of 14.55. The order of ecological risks for the selected metals is As > Hg > Cd > Pb > Cu > Cr > Zn.