Iron deficiency anemia is anemia that occurs when the body’s iron stores do not meet the needs of normal red blood cell production, and is caused by inadequate iron intake, decreased absorption, increased need, and impaired iron utilization or excessive loss. Morphological manifestations are small cell hypochromic anemia. When the medical history is asked, attention should be paid to dietary habits, whether there is paranoia or heterophagia, whether there are digestive system diseases, hookworm disease, etc., whether women have excessive menstruation, whether they have had gastrointestinal surgery, etc. Men and menopausal women should consider whether it is the first symptom of gastrointestinal tumor. Clinical symptoms include fatigue, irritability, palpitation, shortness of breath, dizziness and headache. Children show growth retardation and inattention, and a few severe patients may develop dysphagia, orofacial infection and tongue inflammation. In addition to anemic appearance, physical examination includes dry and wrinkled skin, dry and easy to fall off hair, thin and flat unsmooth nails, and easy to break up. Auxiliary examination small cell hypochromic anemia, male hemoglobin less than 120g/L. female hemoglobin less than 110g/L. pregnant women hemoglobin less than 100g/L. mean red blood cell volume less than 80/μL, morphology can have obvious hypochromic manifestation, serum iron less than 10.7mmol/L, total iron binding capacity more than 64.44mmol/L. pregnancy ferritin saturation Less than 0.15, serum ferritin less than 14mg/L. Bone marrow body staining shows small bone marrow grains, disappearance of stainable iron, iron grains with erythrocytes less than 15%. Treatment is mainly to remove the cause and treat the cause, the second is oral iron, ferrous sulfate is effective and more economical. If oral iron is not tolerated, patients can be treated with injectable iron.