Relapsing polychondritis (RP) is a rare autoimmune disease. Few studies have reported the value of 18F-fluorodeoxyglucose positron emission-computed tomography (18F-FDG-PET/CT) for diagnosis, guiding biopsy and treatment monitoring of RP. 18F-FDG-PET/CT in assessing RP presenting fever of unknown origin (FUO) is not yet reported. To evaluate of 18F-fluorodeoxyglucose positron emission-computed tomography (18F-FDG-PET/CT) for early diagnosis, guiding biopsy and treatment monitoring of relapsing polychondritis (RP), especially for the patient of RP presenting FUO. Consistent with 32 cases had been underwent 18F-FDG-PET/CT scanning, which showed multiple moderately 18F-FDG uptake in the involvement of multiple organs, including the nose, throat, trachea, bronchi, cost cartilage and joint cartilages (SUVmax distribution was 1.93–13.03; mean, 5.02). 50% (16/32) patients were used for PET/CT re-examination after treatment, which revealed that 93.8% (15/16) of patients with RP had decreased obviously for 18F-FDG uptake, with 37.6% (6/16) in decreased substantially and 56.2% (9/16) for disappeared, respectively. The time to diagnosis in these cases was 4.2 months, obviously shorter than the average diagnosis time (20months), showing earlier than conventional method. In addition, biopsies were performed in 56.3% (18/32) of all patients; 94.4% (17/18) cases were positive, which showed useful for targeting biopsy sites. 62.5% (20/32) of all patients presenting FUO had been early diagnosed using 18F-FDG-PET/CT. Treatment monitoring of RP, especially for the patient presenting FUO. It is of great value for monitoring the activity of inflammatory, and guiding the selection of a biopsy site.