The role and efficacy of iron supplementation is twofold: to replenish the raw materials for blood production and to correct iron-deficiency anemia; and to improve the body’s immunity. Iron is one of the indispensable hematopoietic raw materials needed by bone marrow to generate red blood cells. When the human body lacks iron, it first presents as iron deficiency, ferritin gradually decreases, and then iron deficiency anemia occurs. At this time, patients need to actively supplement iron treatment. Iron in the body also plays a role in regulating the body’s immunity, the body’s immunity will be reduced to varying degrees when iron deficiency. In addition, iron deficiency leads to anemia when hemoglobin decreases resulting in a reduction of oxygen carried, resulting in tissue cell hypoxia, the immune system tissue cell function is reduced, which will lead to a decline in the body’s immunity. Iron supplementation for people with iron deficiency can enhance the body’s immunity. Iron supplementation therapy can be categorized into two routes: dietary iron supplementation and pharmaceutical iron supplementation. Food iron supplementation requires eating more lean meat, pig liver, pig blood, spinach and other iron-rich foods. Drug iron supplementation is preferred to oral preparations, such as ferrous succinate tablets, oral solution of iron protein succinate and so on. If there are digestive diseases that cannot tolerate oral iron, intravenous iron sucrose treatment is needed. For patients with iron deficiency, it is more important to identify the causes of iron deficiency, and actively eliminate the causes in order to prevent the recurrence of iron deficiency anemia.