Yin deficiency and internal heat may result in prolonged low afternoon fever, but not in all patients. Yin deficiency and internal heat mostly refers to the deficiency of Yin fluid in the body due to prolonged depletion of heat illness and internal injury to true Yin, resulting in fever when water does not control fire. The patient often appear night heat and morning cool (night temperature rises, the morning back to normal), hands and feet heart fever, the heart of the heat (irritability and sultriness) like cold food, sleep is not stable, night sweating (sleep sweating abnormal, wake up sweating to stop) spermatorrhea and other symptoms, part of the patient will also appear in the afternoon for a long period of time, a low fever phenomenon. However, due to the severity of each patient’s condition, personal constitution and other differences, not all people with Yin deficiency and internal heat will have a prolonged low fever in the afternoon, some patients may not have a high body temperature, only a feeling of heat on the skin, and some patients may have a high fever. People with Yin deficiency and internal heat need to be treated under the guidance of a Chinese medicine practitioner, taking into account their own actual situation, through the methods of nourishing Yin and clearing heat (nourishing the Yin fluid and clearing away the heat) or nourishing Yin and lowering fire (nourishing the Yin essence and lowering the fire).