Objective To investigate the reasons for mis- or missed diagnosis in benign and malignant thyroid noculescancer with contrast-enhanced ultrasound （CEUS） and to improve cognition on CEUS.Methods The images of 25 thyroid nodules which were confirmed by pathology but mis- or missed diagnosed by CEUS in the diagnosis of thyroid cancer were reviewed retrospectively. Results In these 25 nodules，19 benign nodules were misdiagnosed as malignant in which 13 nodules were nodular goiter and 6 nodules were coexisting with Hashimoto thyroiditis. All of the 6 missed malignant nodules were papillary thyroid carcinoma. Among 19 misdiagnosis nodules, hypo-enhancement and iso-enhancement were observed in 13 and 6 nodules in CEUS respectively, and the distribution of microbubbles was inhomogeneous in 16 cases. Among 6 missed-diagnosis nodules, iso-enhancement and hyper-enhancement were observed in 5 and 1 nocules in CEUS respectively, and the distribution of microbubbles was homogeneous in 2 cases. Conclusion The influence of conventional ultrasound，the small volume of nodules and the overlapping imaging features between benign and malignant thyroid nodules in CEUS are the main influence factors for the diagnosis of CEUS. For some thyroid nodules which were difficult to diagnose，we can use fine needle aspiration biopsy to improve the diagnostic accuracy of thyroid cancer.