Abstract: Perfluorooctanesulfonate (PFOS) often co-existed with heavy metals in aquatic environment.To investigate influence of heavy metals on PFOS sorption,sorption isotherms of PFOS on sediment with different concentrations of Cu2+ and Cr3+ in seawater and freshwater were determined.The results showed that both of sorption capacity and nonlinearity of PFOS increased significantly with increasingCu2+,especially when the content of PFOS was at low level.This enhancing effect was more obviously in seawater.Moreover,the effect could also be found in ocean and freshwater system with increasingCr3+,but much weaker than that with increasingCu2+.The above results will provide data to predict and model the transport,distribution and fate of PFOS,and will be helpful for evaluating the ecological risk of PFOS and heavy metals in ocean.