ABSTRACT Objective To investigate the risk of thyroid malignancy in patients evaluated as Bethesda I-V by thyroid ultrasound combined Fine needle aspiration cytology of thyroid (FANC). Methods Sixty-five patients were retrospectively analyzed with thyroid nodules as Bethesda I-V by preoperative FNAC in September 2015 to March 2016.The sensitivity and specificity of the parameters，such as nodules microcalcification，obscure boundary，hypoechoic nodules，aspect ratio and Acoustic halo and acoustic characteristics，were detected.Area of the AUC was calculated using ROC curve to determine the optimal point of diagnosis and assess the diagnostic value. Results The value of ultrasound diagnosis of thyroid nodules is related to the number of positive ultrasound parameters，the risk of malignancy as 12.50%，46.67%，66.67%，81.82%，88.89% and 100% corresponding to the patients with 0，1，2，3，4 and 5 ultrasonographic characteristics. Obscure boundary and aspect ratio has better diagnostic value，the positive predictive value of 90.0% and 90.0% respectively；Nodule size has low diagnostic value，as the positive predictive value of 39.13%；The diagnostic standard of malignant nodules should have at least two positive ultrasound parameters by analysis of the ROC curve，In combination with Bethesda classification of malignant nodules with diagnostic sensitivity 75.00% and specificity of 75.90.Conclusions Ultrasonic In combination with FANC can improve the accuracy of the predicting benign and malignant of thyroid nodules，consequently reducing the diagnostic procedure and excessive treatment.