The sudden high fever in children should be considered as a symptom caused by pneumonia, meningitis or myocarditis, acute gastroenteritis and other diseases. First of all, the cause of the child’s high fever should be clarified, and then go to the hospital for timely cooling treatment.1. Pneumonia: mainly refers to lung infections caused by pathogens such as bacteria and viruses, often with high fever, cough, cough and other symptoms, the type of pneumonia should be promptly identified, and suitable antibiotics should be selected according to the pathogenic bacteria. In case of Streptococcus pneumoniae pneumonia, oral antibiotics can be used for treatment, commonly penicillins, cephalosporins or quinolones, such as amoxicillin, etc. 2. Meningitis: diffuse inflammatory changes in the soft meninges, caused by neurotropic viruses, septic bacteria and other symptoms such as high fever, headache and meningeal irritation signs. Need to follow the doctor’s prescription oral acyclovir, ganciclovir and other drugs for antiviral treatment, or apply ceftriaxone or cefotaxime for anti-infection treatment; 3, acute gastroenteritis: often manifested as nausea, vomiting, abdominal pain, diarrhea, severe cases may appear high fever, dehydration, electrolyte and acid-base balance disorders. Symptomatic supportive treatment mainly for diarrhea and dehydration can be oral intestinal mucosal protectants and adsorbents, such as montelukast, or oral microbial preparations, such as bifidobacteria and Saccharomyces boulardii. Serious patients need to correct acidosis and electrolyte disorders by rehydration; 4. Myocarditis: Myocarditis is an inflammatory disease of the myocardium, which may have symptoms of viral infection 1-4 weeks before the onset, manifested as high fever, dizziness, and weakness. The most appropriate drugs should be selected under the guidance of a doctor, such as creatine phosphate and coenzyme Q to improve myocardial energy metabolism. In addition, infectious diseases such as chickenpox, hand, foot and mouth, measles, as well as allergic diseases, immunodeficiency diseases and tumors can cause fever, which should be treated symptomatically after prompt medical consultation to clarify the cause.