Low fever in lung cancer generally indicates two conditions. Firstly, central type lung cancer with obstructive pneumonia, pulmonary atelectasis and pulmonary infection, its easy to show fever. According to the routine blood examination and sputum culture examination, targeted antibiotic treatment can be selected to control the patient’s infection as soon as possible. If patients with lung cancer have cachexia state and intestinal malabsorption producing diarrhea, they are also prone to diaphoretic infection leading to hypothermia. Sputum fungal examination is needed, and antifungal drug treatment is given if necessary, which can effectively eliminate the phenomenon of hypothermia. Finally, cancer fever caused by lung cancer is also prone to hypothermia in the late afternoon or evening, which is caused by the reabsorption of cancer tissue by the body. Antibiotic treatment is not effective, and hormone and non-steroidal drugs need to be given, which can effectively improve the phenomenon of long-term hypothermia of patients. In conclusion, lung cancer hypothermia needs to be considered as lung infection or reabsorption fever caused by necrotic absorption of cancerous tissues.