Abstract: Objective To evaluate the diagnostic value of conventional ultrasound (US), contrast-enhanced ultrasound (CEUS) and conventional US combined with CEUS for papillary thyroid microcarcinoma. Methods From June 2013 to June 2015, thyroid ultrasound examination was performed to 161 patients with 175 thyroid nodules (≤1 cm) in Chinese PLA General Hospital. Of the 161 cases, there was 29 males and 132 females with average age of (46.2±15.2) years. Of the 175 nodules, 89 nodules were pathologically proved to be malignant and 86 nodules were benign. Pathological type of benign lesions included nodular goiter(n=57), thyroid adenoma (n=16), hashimoto thyroiditis (n=10), subacute thyroiditis (n=3) and all the malignant lesions were papillary thyroid microcarcinoma. Sensitivity, specificity and accuracy of conventional US, CEUS and their combination were calculated to evaluate their diagnostic values. Results Compared with benign thyroid nodules, the intensity of enhancement of CEUS imaging of papillary thyroid carcinoma was lower and later than the surrounding thyroid parenchyma enhancement (P< 0.01). The sensitivity, specificity and accuracy of contrast enhanced ultrasound to diagnose malignant nodules were 89.9% (80/89), 91.9% (79/86), 90.9% (159/175) respectively, and they were 86.5% (77/89), 87.2% (75/86) and 88.9% (152/175) by conventional US, according to the characteristic of morphology, internal echo, calcification, boundary, aspect ratio, and blood flow of thyroid nodules. The sensitivity, specificity and accuracy of conventional US combined with CEUS were 94.4% (84/89), 93.0% (80/86), 93.7% (164/175), respectively. Conclusion Conventional ultrasound can be used as the first choice for distinguishing benign and malignant thyroid nodules, but for some atypical nodules, CEUS can be used as an important assisted method. Conventional ultrasound combined with contrast-enhanced ultrasound can improve the diagnostic accuracy for dignosis of thyroid nodules.