In leukemia, white blood cells may be increased, decreased, or normal, which is not diagnostic, but it is suggestive. If the blood counts indicate abnormally high white blood cells, a preliminary diagnosis of leukemia can be made. The diagnosis of leukemia must rely on bone marrow cytology and genetic testing. Most leukemia patients blood routine generally show elevated, visible variable number of primitive and naïve cells, generally suggesting the possibility of leukemia. Further testing is required. Bone marrow picture is the main basis and mandatory test for diagnosis of leukemia, which can be diagnosed when the primitive cells are greater than 30%, but can also be diagnosed if the primitive cells are less than 20% and leukemia-specific chromosomal alterations can be detected by cytogenetics. When leukemia is suspected, it is necessary to go to a regular hospital in time, complete the test under the guidance of a professional doctor, and make a clear diagnosis, so as to receive targeted treatment under the guidance of a physician.