Tumor fever is often caused by the necrosis of tumor tissue and the release of pyrogen into the bloodstream. Naproxen tablets are often used clinically as a differentiator between tumor fever and infectious fever. If the patient’s body temperature drops to normal after taking naproxen tablets, it means it is tumor fever. If the body temperature does not drop, it can be considered as infectious fever. However, since insidious infection of tumor is more common, we should not consider all fevers of tumor patients as tumor fever, thus delaying the anti-infection treatment. In case of infectious fever, in addition to the conventional antipyretic drugs, active anti-infection treatment is also needed. If the infection in the body is controlled, the fever in tumor patients will also disappear.