Leukemia cannot be judged on the basis of a high number of monocytes. Leukemia is a malignant disease with abnormal differentiation of hematopoietic stem cells, inhibiting normal hematopoiesis, with quantitative and qualitative abnormalities of leukocytes in the peripheral blood, and patients are often accompanied by anemia and thrombocytopenia. The main manifestations are fever, anemia, susceptibility to infection, susceptibility to bleeding, etc. Infiltration of leukemia cells is also found in the organs. Monocytes are only one type of white blood cell, and leukemia is not determined by it alone. The diagnosis of leukemia needs to be confirmed by the comprehensive analysis of a number of tests, such as an increased white blood cell count or an increase in the number of naïve cells in the blood, etc. Bone marrow cytomorphology and pathological examination are important bases for the diagnosis of leukemia. If the test result shows high mononuclear cells, it is recommended to consult a doctor in time to identify the cause of the disease and carry out targeted treatment or therapy.