Leukemia is a malignant proliferative disease of the hematopoietic system that should be treated as early as possible and has the potential for cure. Most pediatric acute leukemias have an acute onset, and some children have fever and rheumatic fever-like bone and joint pain as the first symptoms. In the early stages, there may be anemia, bleeding, lymph node enlargement, and central nervous system damage.1. Fever: The most common symptom, most of them have fever at the beginning of the disease, and the fever pattern is variable, usually not accompanied by chills. Leukemia fever is mostly low fever and antibiotic treatment is ineffective, but in case of co-infection, the fever is persistently high; 2. It is mainly due to the suppression of bone marrow hematopoietic stem cells. It manifests as pallor, weakness, shortness of breath after activity, easy fatigue, etc.; 4. Skin petechiae, petechiae, bleeding from the nose, mouth and gums, gastrointestinal bleeding and hematuria are common. Occasionally, there is intracranial hemorrhage, which can cause death; 5. Lymph node enlargement: enlarged lymph nodes can be palpated locally, and there can be enlarged liver and spleen, and a marked abdominal bulge; 6. Central nervous system damage: headache, vomiting, and even convulsions and coma can occur.