Objective: To investigate the ultrasonographic characteristics and their diagnostic value of medullary thyroid carcinoma (MTC). Methods: A total of 49 nodules in 33 patients with MTC and 108 nodules in 100 patients with papillary thyroid carcinoma (PTC) pathologically diagnosed in our hospital from January 2016 to December 2019 were retrospectively analyzed. The clinical data and ultrasound imaging characteristics of MTC and PTC were compared to analyze the differences in the manifestations of ultrasound imaging. Results: The differences between MTC group and PTC group were statistically significant in ultrasonographic features such as the maximum diameter, shape, boundary, aspect ratio, calcification and blood flow distribution (including internal and peripheral blood flow) and serum calcitonin and carcinoembryonic antigen levels (P<0.05). In addition, 17 patients (51.5%) in the MTC group had cervical lymph node metastasis, among which 14 patients (82.4%) in the lateral group had cervical lymph node metastasis. Conclusion: Compared to PTC, primary ultrasound findings of MTC were as follows: nodules with large volume, clear boundary, regular shape, aspect ratio <1, containing coarse calcification, accompanied by cystic changes, abundant and disordered blood supply, peripheral annular blood flow signals, prone to lymph node metastasis in the lateral group. The combination of serum calcitonin and carcinoembryonic antigen detection is helpful to improve the diagnostic accuracy of MTC.