There are multiple causes for a high fever that does not go away, which may be a bacterial infection, viral infection or other pathogenic infection. In addition, children may have allergies and there is no necessary link between high fever and leukemia. Once a child develops a high fever that does not go away, he or she should immediately go to the hospital for routine blood, biochemical, and coagulation tests, as well as chest and lung CT examinations to rule out the possibility of an infection causing the fever. If infection and other factors are ruled out as the cause of the fever, and if the blood routine suggests the presence of a significant abnormal increase in white blood cells, further morphological verification of the abnormally proliferating cells in the peripheral blood is required. Early fever in childhood leukemia is not a characteristic clinical manifestation, and it is likely that most children do not show obvious temperature abnormalities, but first show malaise, excessive sweating, and loss of appetite, etc. Therefore, there is no necessary connection between high fever and childhood leukemia, and it is necessary to go to the hospital as soon as possible for differentiation.