Fever of 39°C in children without symptoms may be due to infectious or non-infectious factors. Fever in young children may have different causes, including infectious and non-infectious factors. Infectious factors include viral, bacterial, mycoplasma, chlamydia, parasitic and other pathogenic infections. Non-infectious factors such as rheumatic, rheumatoid and other autoimmune diseases, diseases of the blood system can also cause fever, the need to consult a doctor in a timely manner, to do a detailed examination, for the cause of the treatment. Children with fever of 39 ℃ but no symptoms, there may be other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to determine the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.