Recurrent high fever of 39°C in babies mostly occurs because the baby’s nerve center for regulating body temperature is not well developed and mature enough, and the ability to regulate body temperature is relatively poor. In addition, it is also seen in the presence of a more serious pathogen invasion itself, a strong inflammatory response, and a more serious infection, such as septicemia infection in the upper respiratory tract infection and influenza virus infection. It is also common to see the appearance of pulmonary complications, such as bronchitis, pneumonia, or even lung abscess, which can also occur with repeated high fevers of 39°C that do not subside. At this time, blood tests must be performed and chest radiographs taken if necessary to clarify the cause of the disease and provide symptomatic and etiologic treatment.