Leukemia is the most common malignant blood disease in children in China, and the first symptom in most children is recurrent fever, which can be accompanied by skin and mucous membrane bleeding and anemia at the same time. 2. Skin and mucous membrane bleeding: children may have skin and mucous membrane bleeding along with fever, mainly oral bleeding, nasal bleeding and skin bleeding, manifested as bleeding spots or petechiae, and in severe cases, internal organs and intracranial bleeding, which can be life-threatening; 3. Gradually worsen, easily appearing symptoms such as pale face as well as mouth and lips, muscle weakness and low appetite; 4. Other symptoms: such as enlarged liver, spleen, lymph nodes and bone and joint pain. If a child does not meet the above characteristics when having a fever, or if it is not accompanied by other abnormal manifestations, the odds are that it is not leukemia. Of course, the possibility of leukemia cannot be completely ruled out. For recurrent fever in children, it is still necessary to go to the hospital to clarify the cause through routine blood tests and, if necessary, a bone marrow aspiration test may be required. Most recurrent fevers in children may be caused by poor immunity and susceptibility to infection.