The symptoms of low fever caused by tumor are usually not specific, and after excluding other causes, then it is considered to be caused by tumor. When unexplained low fever occurs and lasts for a long time, one should seek medical treatment in time to clarify the cause and exclude the possibility of being caused by tumor, and the cause of low fever can also be clarified through blood and imaging tests. Low fever caused by tumor generally has the following characteristics: 1. General antipyretic drugs are ineffective: when patients have low fever for a long time, the effect of antipyretic drugs is not obvious, and low fever can be relieved by antitumor drugs; 2. No abnormality in blood test: for most of the disease-induced fever, the elevation of white blood cells and the accelerated sedimentation rate can be seen after the blood test. However, for low fever or even high fever caused by tumor, the value will not be changed after blood checking; 3. Occupying lesions in imaging: when the patient has low fever for a long time, and occupying lesions can be clearly observed after imaging examination, it should be considered whether it is caused by the tumor or not; 4. Accompanying symptoms: when the patient, besides the symptoms of low fever, has symptoms of lethargy, anemia, mental depression, etc., it should be considered whether the symptoms are caused by the tumor or not. tumor. Therefore, when the patient has low fever, to determine whether it is caused by tumor, we should firstly observe the time of fever, improve the relevant examination in time, and analyze the symptoms together with other symptoms of the patient, and exclude the infection and other factors of fever, and then finally consider the tumor fever, so the tumor fever belongs to the exclusionary diagnosis.