Fever usually refers to the axillary body temperature above 37.3 ℃, and the causes of fever are usually divided into two categories: the first type of infectious fever refers to the fever caused by the invasion of various pathogens such as bacteria, viruses, Mycoplasma pneumoniae, Rickettsia, fungi, spirochetes and parasites; The second type of non infectious fever is fever caused by chronic diseases in most patients. Infectious fever is the normal protective response of the body's immune system to the attack of pathogens, indicating that various immune cells in the body are fighting against pathogens. The fever characteristics and accompanying symptoms of different pathogen infections are also different. A variety of infections can lead to fever, such as upper respiratory tract infection, otorhinolaryngology infection, lung infection, intestinal infection, urinary tract infection and so on. Novel coronavirus pneumonia is also needed to screen for fever patients in the normalization of epidemic prevention and control. For patients with fever above 37.3 degrees, cough, fatigue, sore throat, smell loss, diarrhea and so on must be treated in fever clinic. (outlook new era)