Abstract: The incidence of differentiated thyroid cancer (DTC) is increasing annually, and most patients have excellent prognoses. However, the survival rate decreases significantly in patients with recurrences and metastases. Therefore, the detection, evaluation, and treatment for the recurrences and metastases of DTC are particularly crucial. With the continuous progress of PET/CT research in oncology, its application value has received increasing attention in such patients; it also provides important information for accurate diagnoses and treatment methods. In this study, the authors review the application progress of PET/CT in the diagnosis of recurrences and metastases of DTC.