Usually, cardiac insufficiency means heart failure, and patients with heart failure usually do not develop fever. However, if there is a concurrent respiratory infection, fever may develop. Heart failure may be due to myocarditis, myocardial ischemia, cardiac overload, constrictive pericarditis and other factors causing patients with myocardial diastolic and systolic dysfunction, insufficient cardiac output, causing circulatory dysfunction caused by the patient, usually does not have a fever manifestation. The main manifestations are dyspnea, fatigue, drowsiness and other symptoms. However, if the patient’s heart failure causes pulmonary stasis and respiratory tract infection, it may be the patient’s local inflammatory reaction, and the inflammatory factor will stimulate the patient’s thermoregulatory center, which may cause the symptoms of fever. If the cause of the patient’s heart failure is endocardial infection, the phenomenon of heart failure combined with fever may occur, usually in patients with structural changes of the heart. Blood bacterial culture should be performed actively and antibiotic treatment should be applied promptly. If the symptoms of fever appear in patients with cardiac insufficiency, it is recommended that patients pay attention to timely medical treatment to avoid delaying the condition.