Anemia should be defined as a reduction in the total volume of red blood cells in the systemic circulating blood to below normal values. Usually, anemia is defined as the concentration of hemoglobin in the peripheral blood is lower than the normal standard for the same age group of the patient’s gender and region. The hemoglobin of adult men in coastal and plain areas of China is lower than 120g/L, and that of adult women is lower than 110g/L. However, this standard is not suitable for highland areas, where the normal hemoglobin should be higher due to the lack of oxygen, and the normal value of hemoglobin of children under 12 years old is about 15% lower than that of adult men, and there is no significant difference between the two sexes. The signs and symptoms of anemia are mainly weakness, fatigue, depression, general debility, specifically pale skin, nail bed, oral mucosa and conjunctiva, feeling shortness of breath and palpitations when physical activity increases, and angina pectoris may appear in elderly patients. The central nervous system may experience dizziness, headache, syncope, ringing in the ears, blurred vision, inattention, and numbness and pins and needles in the hands and feet. Female patients often have irregular menstruation or amenorrhea, and male patients often have decreased libido. Loss of appetite is a common symptom, and abdominal flatulence, nausea, constipation or diarrhea may also occur. Dry skin, lack of luster of hair, flattened or retrorse nails can be seen in iron deficiency anemia, severe anemia can have low fever, high fever is often caused by the primary disease or complications. The treatment of anemia should first remove the cause of the disease, while using measures to directly correct the anemia or temporarily reduce it. Bleeding from various causes is one of the common causes of anemia and should be treated accordingly and appropriately, for example, excessive menstruation or uterine bleeding treated with hormone therapy or surgery, bleeding from hemorrhoids, bleeding from stomach or colon cancer treated with surgery. Bleeding from gastric or duodenal ulcers treated with medical or surgical procedures can usually stop the bleeding and cure the anemia. For anemia caused by nutritional deficiency, iron, vitamin B12 or folic acid can be supplemented. Parasites can be treated with deworming. If there is infection or inflammation, apply antibiotics promptly. Severe anemia can be treated with blood transfusion or rapid reduction or elimination of symptoms. Splenectomy is feasible for certain anemias such as hereditary spherocytosis, because the spleen is the main organ that destroys blood cells and is also associated with antibody production. Bone marrow transplantation is primarily used to treat acute aplastic anemia and, if successful, can lead to a cure for this severe form of anemia.