Thyroid cancer is often accompanied by ipsilateral cervical lymph node metastasis, which can involve all regions of the neck except the chin region. Most of the metastatic lymph nodes are around the internal jugular vein, while the metastasis can be to the posterior cervical triangle or to the mediastinal lymph nodes, but rarely to the submandibular region. Even in patients with clinically negative cervical lymph nodes, 50% of postoperative cervical lymph node specimens are still metastatic on pathological examination. In patients with clinically palpable enlarged lymph nodes, postoperative pathology confirms essentially 100% of cancer metastases. Under normal circumstances, superficial cervical lymph nodes are not enlarged. Once enlarged, especially between the anterior cervical band and sternocleidomastoid muscle, it means that there is retrograde lymphatic metastasis, and the metastatic foci of cervical lymph nodes can penetrate the lymph node envelope and fuse into a mass or invade adjacent blood vessels, nerves and surrounding soft tissues. Contralateral lymph node metastasis occurs in approximately 4% of cases. Among malignant tumors, the prognosis of thyroid cancer is generally good, and many thyroid cancers have metastases, but patients can still live for more than 10 years. There are many factors involved in the prognosis, such as age, gender, pathological type, extent of the lesion, metastasis and surgical approach, among which the pathological type is the most important. Patients with well-differentiated thyroid cancer can survive for a longer period of time in 95% of cases, especially papillary carcinoma which has good biological characteristics and the best prognosis, but a few of them can become undifferentiated carcinoma with very high malignancy; undifferentiated carcinoma has the worst prognosis and patients often die within six months. The larger the size of tumor, the more chances of infiltration, and the worse its prognosis. According to the relevant statistics, the presence or absence of lymph node metastasis does not affect the survival rate of patients; the uncontrolled primary tumor or local recurrence can lead to higher mortality rate, and the degree of direct tumor spread or infiltration is more important than lymphatic strongba metastasis.