Carbon/sulfide/iron relationship and sulfate reduction rate were investigated in the East China Sea continental shelf sediments. The area is characterized by median to high sulfate reduction rate, and high concentrations of iron oxide minerals. Organic carbon was found to be the primary limiting factor for the pyrite formation. Sulfate reduction rate increased with increasing organic carbon concentration. C/S ratio displays a typical normal marine sediment ratio. Low DOP values and abundance of highly reactive iron oxide, ferrihydrite and lepidocrocite, indicate that iron is not limited in the East China Sea continental shelf.