ABSTRACT Objective To analyze the ultrasonographic features of medullary thyroid carcinoma and differentiate it from thyroid follicular adenoma.Methods Retrospective analysis of the ultrasonographic features of 79 MTC patients with 85 nodules，76 FTA patients with 77 nodules as control group，compare the difference between the MTC and FTA in age，location，size，shape，boundary，acoustic halo，calcification，and peripheral blood flow and other aspects.Results MTC group and FTA group compared to the age：differences between the two groups was not statistically significant，P=0.957.There is a significant difference between the gender，P=0.000.The maximum diameter of nodules；there is a significant difference，P=0.000.Distribution of nodule location have significant difference，P=0.000.Comparison of two groups of ultrasound image features：boundary （P=0.000），morphology （P=0.000），echo （P=0.000），component （P=0.000），calcification （P=0.01），aspect ratio （P=0.003），acoustic halo （P=0.000），peripheral blood flow （P=0.000） between the two groups was statistically significant differences.Internal blood flow there was no statistical significance （P=0.579）.Lymph node metastasis was found in 27 cases of MTC.Conclusion MTC has the characteristics of patients with slightly female more than male，compared with FTA，the volume of MTC is less than FTA，the boundary is not clear and irregular in shape to see more，hypoechoic cystic small aspect ratio is less than 1，halo rare and uneven thickness，microcalcification，internal blood flow is disordered，peripheral blood flow is not complete.