Objective To explore the role of ultrasound-guided core needle biopsy in diagnosis and treatment of thyroid nodules.Methods 778 cases undergoing ultrasound-guided core needle biopsy in our department from Jan.2012 to Dec.2014 were retrospectively analyzed,and the sensitivity,specificity and accuracy were calculated.Results All the patients were operated successfully.Except for 21 nodules undiagnosed,16.4％ (124/757) were histologically diagnosed as malignant and 83.6％ (633/757) were benign.15 samples of the 124 malignant nodules were less than 10 millimeter in diameter.The sensitivity,specificity and accuracy were 100％,94.8％ and 95.6％,respectively.Of the ultrasound features,blood flow,boundary,internal situation and calcification were statistically significant between benign and malignant nodules,but not so between the groups of different greatest dimentions.Conclusion Ultrasound-guided core needle biopsy is safe and effective for obtaining thyroid nodule tissue,and it is helpful for diagnosis of thyroid diseases.