The recovery time for severe anemia is closely related to the type of disease and the individual patient’s condition, and cannot be generalized. Severe anemia is defined as hemoglobin less than 60g/L in the blood, and patients will experience dizziness, headache, limb weakness, chest tightness, panic, shortness of breath, etc. If it is caused by iron deficiency anemia, most patients will return to normal after 3-4 months through calcium supplementation and diet adjustment. If it is megaloblastic anemia, patients will gradually recover in 2-3 months after vitamin B12 and folic acid supplementation. In case of severe anemia due to neoplastic diseases, acute leukemia and other malignant diseases, the recovery time of the patient cannot be predicted and the original disease needs to be removed in time for recovery to be possible. Severe anemia is only a symptom of the disease and requires timely consultation with the hematology department to identify the cause and treat the cause before the anemia can be recovered.