Bacterial fever according to the different pathogens of infection, the actual period of fever has obvious differences, but the majority of patients in about 3~5 days. Fever is a manifestation of thermoregulatory dysfunction produced by the body under the action of a pyrogen. Bacterial infection is one of the most important clinical causes of fever, which usually occurs in the acute phase of the infection, and most of the fever lasts for 3~5 days in the context of current medical treatment, such as acute pharyngeal tonsillitis, bacterial pneumonia, and so on. Certain bacterial infections may become chronic due to inappropriate treatment, and their febrile period may be prolonged, for example, chronic pyelonephritis. In addition, due to the different pathogens, the patient’s fever period may last for weeks or even years, such as typhoid fever and tuberculosis. If fever occurs after a suspected bacterial infection, patients should consult a doctor in time and receive standardized anti-infective treatment under the doctor’s guidance, and should not use antibiotics and other drugs on their own.