Objective To explore the clinical values on 131I ablation for residual normal thyroid tissues in postoperative differentiated thyroid carcinoma (DTC) patients. Methods 115 patients of postoperative thyroid cancer were treated with 131I to ablate for residual normal thyroid tissues. 2.96~3.7GBq of 131I ablative dose was administrated. Thyroid extract was given for 3 months, and then stopped. 50 μg of T3 daily was given for 15 days and stopped for over 15 day. The 131I whole-body scan were performed. Results The effective rate of 131I ablation for residual normal thyroid tissues in postoperative was 70%. Conclusion The effect of 131I ablation for residual normal thyroid tissues in postoperative thyroid cancer patients is very good. It can prevent recur and discover transform of thyroid cancer patients.