Simple fever in children can be seen in early childhood emergency rash, urinary tract infections or atypical Kawasaki disease, etc., specific need to be analyzed according to the child’s situation to determine. 1. Acute rash in young children: common in infants and young children, caused by human herpes virus infection, the course of the disease is often manifested by recurrent fever, there may be no other obvious abnormal symptoms, the general situation can be, often fever for 3 to 5 days, rash, body temperature returned to normal. 2. Urinary tract infection: it can be caused by Escherichia coli, etc. Clinical symptoms of fever may appear, some children may have symptoms such as urinary frequency and urgency, and some children only show symptoms of fever, and perfect routine urinalysis can assist in the diagnosis. 3. Atypical Kawasaki disease: Clinical symptoms may only include recurrent fever, ineffective treatment with antimicrobial drugs, rash, chapped lips and other symptoms are not obvious, and coronary artery dilatation can be seen on cardiac ultrasound in some children. 4. Other: such as acute leukemia, there may be no fixed fever type of fever, perfect blood test can be seen obvious abnormality, lumbar puncture examination can assist in the diagnosis. It is recommended to actively consult a specialist physician to evaluate and determine the cause of the disease.