Chronic blood loss, or a lack of hematopoietic substances, should be considered when anemia persists one year after colon surgery. At this point the patient should go to the hospital to check the degree of ischemia and the cause. Anemia after colon surgery is considered to be chronic blood loss. If the surgical wound ruptures after colon surgery, it is likely to cause long-term chronic bleeding. If the patient’s primary disease is cancer, tumor recurrence or metastasis may also cause chronic blood loss. In this case, further diagnosis should be made to understand the condition, and then the patient should be treated with surgery, radiotherapy or chemotherapy under the advice of the doctor. Blood loss after colon surgery may also be due to the lack of hematopoietic substances, such as folic acid, vitamin B12 deficiency will cause megaloblastic anemia, folic acid and vitamin B2 deficiency will lead to red blood cell DNA synthesis disorders, which will cause the patient to be anemic. Prolonged anemia will make people feel tired and sleepy, and in serious cases, it will cause insufficient blood supply to the cerebrovascular, cardiac and renal organs. Patients who are still suffering from anemia one year after the operation should follow the doctor’s instructions to treat the anemia actively.