Abstract: The heavy metals(Hg, As, Cu, Pb, Zn, Cd, Cr) were analyzed for 241 surface sediment samples collected over intertidal mud flat of Northern Yancheng. Then we studied their spatial distribution patterns, and correlations among heavy metal concentrations. The ecological risk regarding heavy metals was assessed by using Hakanson Potential Ecological Risk Assessment Mothed.(1) The concentrations of Zn, Pb and Hg reached National First-class Sediment Standard. However, only most samples of Cr, Cd, Cu concentrations reached National First-class Sediment Standard, others meeting National Second-class Sediment Standard.(2) The source and accumulation of Cu, Pb, Zn and As were similar. The Cd concentration was not grain-size dependent.(3) We concluded that the potential ecological risk was low in the study area. The potential ecological risk was Cd Hg As Cu Pb Cr Zn.