Abstract: Iron is an essential element for the growth of marine phytoplankton and has an important impact on marine primary productivity. Dissolved chemical reactive iron is an important component of total dissolved iron and most easily absorbed and utilized by phytoplankton. Although great progress has been made in the determination of iron in seawater, there is still large space for development in the method of iron speciation analysis. This paper systematically summarized the speciation analysis methods of iron in seawater, especially the research progress of electrochemical detection of chemical reactive iron, and looked forward to the development and application of electrochemical methods in the field and rapid analysis of dissolved reactive iron in seawater. This review aims to provide technical reference for the in-depth study of the existing forms, distribution rules and transformation mechanism of iron in seawater, and improve our understanding of the biogeochemical cycle of iron and the ecological effects of offshore environment.