Recurrent fevers with low ultra-sensitive C-reactive protein need to rule out viral infections, Mycobacterium tuberculosis infections, and non-infectious causes of fever such as tumors. Ultrasensitive C-reactive protein is one of the most important non-specific indicators of bacterial infection, suggesting an inflammatory response, and the higher the ultrasensitive C-reactive protein, the more serious the infection. The higher the ultra-sensitive C-reactive protein, the more serious the infection. Low ultra-sensitive C-reactive protein and recurrent fever need to further improve the viral test indicators, such as EBV, cytomegalovirus, influenza virus, coronavirus, etc., to rule out viral infections caused by fever. Non-infectious fever such as drug fever, tuberculosis fever, tumor fever, central fever, and fever caused by connective tissue disease should also be further excluded. In conclusion, patients with recurrent fever due to lowered ultra-sensitive C-reactive protein should consult a doctor for a detailed examination and a clear diagnosis for targeted treatment.