Objective To systematically evaluate the efficacy and safety of 125I seed implantation on the treatment of refractory thyroid carcinoma.Methods A total of 14 patients with refractory thyroid carcinoma received CT and ultrasound image-guided 125I seed implantation in our hospital from Apr.2003 to Oct.2016.The radioactive activity ranged from 0.3 to 0.8 mCi,and the prescribed doses were 80 to 120 Gy.11 patients were diagnosed as differentiated thyroid carcinoma and 3 patients were medullary thyroid carcinoma.The local control rate,pain relief and complications were observed.Results The patients were followed up from 12 to 96 months.Two months after treatment,complete remission happened in three patients,partial remission in nine,and disease stability in two,no patients with progression.The half year,one year,two year local control rate was 100％,92％ and 42％,respectively.Seven patients were evaluated using number rating scales and obtained a score of 4.14±1.68 before therapy.Two months after treatment,the score was reduced to 2.00±1.15 (P＜0.000).No usual complications occurred during or after treatment except for I acute skin radio reaction in 4 cases.Conclusion 125I seed interstitial implantation for refractory thyroid carcinoma under guidance of ultrasound or CT is efficient and safe.