Chronic myelogenous leukemia (CML) is the first blood cell disease to be recognized among leukemias, and its clinical manifestations and hematological examinations have their own particularities. Chronic leukemia is less common in children, accounting for about 3% to 5% of childhood leukemia, of which chronic myeloid leukemia is the main one. The disease is characterized by elevated white blood cells and splenomegaly, and after blast transformation, it presents as acute leukemia. The clinical and biological characteristics of CML in infancy are significantly different from those of adult CML, so it can be divided into two types: adult type and juvenile type. The pathogenesis of CML is still unknown. It is generally believed that this disease is a pluripotent hematopoietic stem cell disease, and its occurrence is related to certain chemicals and genetic factors.