Leukemia, commonly known as blood cancer, is a disease caused by cancer in the leukocyte system of the body’s hematopoietic factory —– bone marrow. Before the 1970s, leukemia was almost incurable, but with the development of science and technology, research on leukemia has become more and more advanced, and many new chemotherapeutic drugs have been developed, and there have been breakthroughs in the treatment of leukemia, especially in children with acute lymphoblastic leukemia. More than 80% of children with the disease can be cured. Early detection, early diagnosis, and regular chemotherapy are very important for the treatment of leukemia. Fever is the most common first symptom of childhood leukemia. More than half of the children have varying degrees of bleeding, mainly from the nasal mucosa, mouth, gums and skin, or in severe cases, blood in the stool, hematuria or even intracranial hemorrhage. Anemia is often the most common early symptom and worsens progressively. The child has a pale complexion and mucous membranes, weakness and low appetite. In addition, children with leukemia may develop enlarged liver, spleen and lymph nodes. Pain in bones and joints. Headache, nausea, vomiting, and even convulsions and coma are signs of leukemia central nervous system infiltration. Boys may present with painless enlargement of the testicles. Parents who find that their children have pallor, weakness, bone and joint pains, unexplained fever, and incessant bleeding, or blood tests that reveal abnormally elevated or reduced white blood cells and severely reduced hemoglobin and platelets, should immediately take their children to a hospital hematology specialist for examination.