Ferric carboxymaltose is a new type of intravenous iron agent, which is a complex formed by the trivalent polynuclear iron core surrounded by carboxyl maltodextrin. This core-shell structure can stably complex iron and control the release of iron, so it can prevent the toxic oxide produced by the saturation of iron transporter and ferritin caused by high blood iron concentration. Carboxymaltose iron has high iron content, less administration times and good iron supplementation effect, which greatly improves the compliance of patients. It is a good intravenous iron supplement.