Objective To summary the experience in diagnosis and surgical treatment of differentiated thyroid carcinoma (DTC). Methods The clinical data and follow-up results of 167 cases of DTC were retrospectively analysed. Results (1) The accurate rate of preoperative cytology diagnosis was 76.9%(97/126). (2)121 patients were diagnosed as thyroid carcinoma before or during operation. Histologic examination after primary operation revealed that the carcinoma spread to the isthmus and the opposite lobe in 5 cases. 57 cases were followed up with only 2 cases recurred 2 and 3 years after the operation, and 3 died 6 to 10 months after operation. (3)87.5%(42/48)cases of the reoperation were due to misdiagnosis as benign lesions in primary operation. Histologic examination revealed that residual tumor in the remnant thyroid tissue was found in 45.2%(19/42)cases, and residual tumor in the lymph nodes of the suffered side in 19.0%(8/42)cases. 30 cases were followed up without any recurrence. Conclusions (1) Cytological diagnosis must be paid great attention to preoperatively; (2) Excision of the suffered lobe, isthmus and greater partial of the opposite lobe, along with clearing the enlarged lymphnodes of the isolateral side are generally performed for the DTC; (3) Reoperation due to misdiagnosis as benign lesions in primary operation must remove the remnant tissue of thyroid and the isolateral lymphnodes. The cases should also be followed up even if enough excising is performed in primary operation.