Medullary thyroid carcinoma is relatively rare compared to other types of thyroid cancer, is an APUD tumor, and the tumor can secrete calcitonin. In general, medullary thyroid carcinoma is rare and accounts for about 5% to 10% of thyroid cancers. Medullary carcinoma occurs in parafollicular cells and belongs to APUD tumors. This kind of carcinoma occurs at the age of 40-60 years, and its malignant degree is higher than that of follicular carcinoma and papillary carcinoma, and lower than that of undifferentiated thyroid cancer. A big feature of medullary carcinoma is that the cancer cells can secrete calcitonin, and some people can develop severe diarrhea and hypocalcemia. Pathologically, the arrangement of cancer cells shows a nested or fascicular arrangement, and although there are no papillary or follicular structures in them, there are amyloid deposits in their interstitium. Its biological characteristics are again different from those of undifferentiated carcinoma. Medullary thyroid carcinoma is moderately malignant, and metastases include cervical lymph node metastasis and blood line metastasis. Treatment continues to be a combination of mainly surgical procedures. After the diagnosis of medullary thyroid carcinoma, it is necessary to actively consult the doctor and follow the doctor’s instructions for reasonable treatment.