Whether anemia is caused by tumor can be identified by history, clinical manifestations and examination. 1. Medical history: whether the patient with anemia has tumor history and family history of tumor. For example, digestive system tumors (stomach cancer, intestinal cancer, etc.) can directly affect the absorption of hematopoietic substances, and anemia symptoms will appear in the long run. 2. Clinical manifestations: in addition to clinical manifestations related to anemia, patients with anemia may also have tumor-related clinical manifestations, the type and degree of which vary according to tumor types. For example, gastric cancer may have nausea, vomiting and epigastric discomfort in addition to anemia; lung cancer may have long-term chronic dry cough, blood in sputum with anemia. 3. Examination: blood routine indexes, such as red blood cells, white blood cells, platelets, hemoglobin and so on, as well as bone marrow cytology analysis can be examined to exclude the problem of hematopoietic function itself. If the above symptoms occur, it is recommended to go to the hospital in time for consultation and early and regular treatment under the guidance of physicians.