Objective To analyze the imaging of 18F-FDG PET/CT scan for the patients with primary thyroid lymphoma (PTL). Methods Between November 2009 and August 2013, 12 patients with primary thyroid lymphoma (PTL) were histopathologically diagnosed in 805 lymphoma patients. 18F-FDG PET/CT scan was performed before any therapy. The imaging was analyzed in all patients with PTL. The relationship between clinic factors and SUVmax value was also evaluated. Results PTL developed mostly in middle-aged and older females. Diffuse large B-cell lymphoma (DLBCL) and Mucosal-associated lymphoid tissue lymphoma (MALToma) were major histological types of PTL. Unilateral or bilateral enlargements of thyroid were detected in 18F-FDG PET/CT imaging of all patients with PTL, with homogenous, hypodensity and hypermetabolic lesions (CT value, 49.4±11.8HU; SUVmax value, 12.4±8.7). SUVmax value of thyroid had no relevant with age, gender, B symptom, and stage (P>0.05), but had a relationship with IPI score (P=0.018). Conclusion 18F-FDG PET/CT imaging can help early diagnosis the patients with PTL.