Objective To explore the value of ultrasound-guided core needle biopsy (CNB) in diagnosis of thyroid nodules.Methods The clinical data of 395 patients with thyroid nodules who underwent ultrasound-guided CNB were retrospectively analyzed,and the results of CNB pathology of 278 patients who endured surgery were compared with postoperative wax pathology results.Results All patients completed CNB successfully and satisfaction rate for tissue samples was 100％.Local hematoma occurred in one case and relieved by conservative therapy.The CNB pathology results of 278 cases of patients were as follows:92 cases were malignancy,including 91 cases of papillary thyroid carcinoma,lcase of medullary thyroid carcinoma; 182 cases were benign,including lcase of parathyroid adenoma,48 cases of adenoma,and 133 cases of nodular goitre and other nodular affection.In 278 patients who underwent surgery,the CNB pathology results in 273 cases,including 90 malignancy cases and 183 benign cases,were consistent with postoperative wax pathology results and false positive occurred in 1 cases,ambiguous occurred in 4 cases.So the accuracy,sensibility,specificity,missed diagnosis rate,and misdiagnosis rate of ultrasound-guided CNB for differential diagnosis of thyroid malignant nodules from benign nodules were 98.20％ (273/278),95.79％ (91/95),99.45％ (182/183),4.21％ (4/95) and 0.55％ (1/183).Conclusion Ultrasound-guided CNB has important value on differential diagnosis of thyroid nodules.It is safe and effective.