1, the number of nodules: mostly single, a few are multiple. However, with the application of high-frequency ultrasound, many tiny nodules can be detected, so the value of single or multiple nodules as a judgment of benign and malignant is getting smaller. 2. Internal echogenicity of the nodules: most of them are hypoechoic, and isoechoic or hyperechoic are rare. However, low echogenicity inside the lesion does not mean that it is malignant, because 90% of thyroid nodules can be hypoechoic; in addition, the internal echogenicity of malignant nodules is more than “uneven” and the posterior echogenicity is diminished or disappears, which can be distinguished from the “uniform hypoechogenicity” of benign nodules. This can be distinguished from the “homogeneous hypoechogenicity” of benign nodules. 3, the longitudinal ratio of the nodule: the longitudinal ratio is close to 1, the peripheral boundary is unclear, the shape is not regular, or it becomes crab foot-like, and there is no or no complete acoustic halo (dark ring) around the mass, etc. should be considered as malignant possibility. 4, nodule growth rate: faster growth rate (different time ultrasound comparison), rapid increase in nodules within a short period of time, after excluding intracapsular hemorrhage, should be highly suspected of malignancy. 5, nodal calcification: calcified foci are generally divided into microcalcifications, coarse calcifications, and circular calcifications. At present, scholars at home and abroad generally believe that microcalcifications are the most specific index for the diagnosis of thyroid cancer, especially for papillary carcinoma, which can reach over 90%. In addition, in young patients (less than 40 years old), if calcification is found in a single nodule, the possibility of malignancy increases 4 times. 6. Lymph node metastasis of thyroid cancer: The ratio of long to short diameter of metastatic lymph nodes of thyroid cancer is less than 1.5 in most cases. In the advanced stage, the ipsilateral internal jugular vein and carotid artery and trachea may be involved or adhere to the anterior cervical muscle. Color Doppler flow imaging features: Color Doppler flow imaging is divided into four types according to the distribution of blood flow within and around the tumor: Type I: no internal blood flow; Type II: little internal blood flow; Type III: peripheral blood flow; Type IV: internal linear branching blood flow. The distribution of blood flow in malignant nodules is mostly type III and IV. In malignant nodules, due to high metabolism and rapid value-added of tumor tissue, the new blood vessels lack smooth muscle and have thin walls. Therefore, if the high speed flow signal in thyroid nodules is greater than 70cm/s, cancer should be considered as a possibility.