Ultrasound is a non-invasive test that is easy to perform and can be repeated to determine the location, size, number and extent of the lesion and whether the lymph nodes are metastatic. Ultrasound is an important adjunct to early detection and diagnosis of differentiated thyroid cancer, and as a routine test for thyroid cancer diagnosis, it can effectively reduce the rate of missed diagnosis and misdiagnosis. CT has good sensitivity and accuracy in detecting the extent and number of the masses, the invasion of the adjacent trachea, and the presence of enlarged lymph nodes in the paratrachea, around the internal jugular vein, and the upper mediastinum. At present, the last resort for definitive diagnosis of differentiated thyroid cancer is still frozen section at surgery and postoperative paraffin section. Pathological examination can determine its pathological type and provide a basis for selecting the correct treatment plan. In case of any of the following: ① single solid nodule in male thyroid gland; ② fast growing, hard and fixed nodule in the recent past; ③ enlarged and hard lymph nodes in the ipsilateral neck; ④ invasion of the recurrent laryngeal nerve and adjacent organs of the trachea. For those with high suspicion of malignancy, intraoperative rapid frozen section should be performed to determine the nature and select the correct surgical approach. The scope of surgical resection for primary foci of differentiated thyroid cancer is not yet uniform. At present, the following four surgical procedures are acceptable: ① total excision of the affected gland lobe + isthmus; ② total excision of the affected gland lobe + isthmus + major contralateral excision; ③ near total thyroidectomy; ④ total thyroidectomy. Other surgical procedures such as partial thyroidectomy and unilateral or bilateral major thyroidectomy are not standardized and should be discarded as they are the main causes of cancer residue and recurrence. Our experience is that the scope of resection for differentiated thyroid cancer should be individualized according to the patient’s clinical stage and risk factors: for low-risk patients, total excision of the affected lobe + isthmus or total excision of the affected lobe + isthmus plus postoperative thyroxine suppression therapy will result in lower complication rate and higher quality of life; for high-risk patients, near-total thyroid excision or total thyroid excision plus postoperative thyroxine suppression therapy will result in lower complication rate and higher quality of life; for high-risk patients, near-total thyroid excision or total thyroid excision will result in lower complication rate and higher quality of life. For high-risk groups, near-total thyroidectomy or total thyroidectomy with thyroxine suppression is effective, but the risk of surgical complications is relatively increased. For patients with low risk factors, total lobectomy + isthmus or total lobectomy + isthmus + major contralateral resection is performed. For patients with high-risk factors, a sub-total thyroidectomy or bilateral total thyroidectomy is performed. Although total or sub-total thyroidectomy has some complications, it is not likely to have serious complications with good technique and careful operation. Indications and scope of peripheral lymph node dissection for differentiated thyroid cancer Since Crile reported cervical lymph node dissection in 1906, it has been clinically agreed that cervical lymph node dissection should be performed for those with clear lymph node metastasis. However, there is disagreement on whether to perform elective cervical lymph node dissection in patients with negative clinical N0 (cN0) lymph nodes, i.e., no abnormally enlarged lymph nodes are clinically detected. Some do not favor prophylactic cervical lymph node dissection because the 10- and 15-year survival rates do not differ significantly from those of curative cervical lymph node dissection. The areas most likely to be involved in thyroid cancer are zones II, III, IV, V and VI. Zone VI should be routinely cleared because it has the highest metastasis rate; Zone I is rarely involved and is excluded from routine surgical clearance. In the literature, the incidence of lymph node metastasis in zone VI of thyroid cancer is relatively high, ranging from 70.4% to 76.0%. The lymph nodes in region VI are the first metastatic area of thyroid cancer, and routine debridement is helpful to reduce the incidence of lymphatic metastasis in other regions, so the treatment of lymph nodes in region VI is beneficial to improve the survival of thyroid cancer patients. Lymph node removal in the neck should be firmly eliminated, it can neither be cleared completely nor make re-operation extremely difficult and increase post-operative complications. Endocrine therapy should be given after surgery for differentiated thyroid cancer. Oral thyroxine tablets or levothyroxine tablets should be given with the aim of suppressing the secretion of TSH so that the level of TSH in blood decreases and the residual microscopic cancer slows down its growth or even disappears. The purpose of giving supraphysiological amount of thyroxine – levothyroxine sodium to thyroid cancer patients is to inhibit the secretion of TSH from the pituitary gland, so as to reduce the recurrence and metastasis of thyroid cancer If total thyroidectomy is not performed, it can generally be taken for l to 3 years, and it is not necessary to take it for life to keep TSH at low level. 2006, experts from 3 disciplines, namely endocrinology, surgery and nuclear medicine The 2006 guidelines for the management of DTC based on evidence-based medical evidence recommend that TSH should be suppressed to <0.1 mU/L in high-risk patients (level B recommendation). In low-risk patients, TSH should be suppressed to 0.3-2.0 mU/L (Class C recommendation), and mild increase in T3 and T4 is appropriate. Tumor size, number of lesions, cervical lymph node metastasis and age should be used as the basis for selecting the surgical approach for differentiated thyroid cancer, and lymph node dissection in the central region should be routinely performed for high-risk patients.