Abstract: A special feature of the case reported in this paper is that no definite primary lesion was found by pathology after total thyroidectomy and neck lymph-node dissection. PET/CT examination and whole-body ¹³¹I scan after radioiodine therapy revealed a left iliac bone lesion, which was resected accordingly. In addition to the pathological confirmation of another bone metastasis of papillary thyroid carcinoma, ¹³¹I therapy and regular thyroid-stimulating hormone-suppression therapy were performed again. Regarding the diagnosis and treatment process, the diagnosis was constantly updated and the targeted treatment plan was prepared. Finally, effectively treatment on the patients was achieved.