131I is an important tool for the treatment of differentiated thyroid cancer (DTC). With the gradual increase in the incidence of DTC, the concept of treating this disease with Wenqiang 131I at the Department of Nuclear Medicine, Sino-Japanese Friendship Hospital of Jilin University has been updated in recent years. The Nuclear Medicine Branch of the Chinese Medical Association has organized the preparation of “Guidelines for 131I Treatment of Differentiated Thyroid Cancer”. The following is a summary of expert recommendations. The main point of evaluation of thyroid nodules is the differentiation of benign and malignant. Emphasis is placed on evaluating thyroid nodules with a family history of thyroid cancer, history of neck irradiation, age, and gender associated with malignant features. Serum TSH levels should be routinely measured in patients with thyroid nodules. Serum Tg is not recommended to assess the benignity or malignancy of thyroid nodules. Thyroid nodules >1 cm in diameter with decreased serum TSH should undergo thyroid 131I or 99Tc nuclide imaging to determine whether the nodule has autonomic uptake. CT, MRI and 18F-FDGPET are not recommended as routine methods to assess the benignity or malignancy of thyroid nodules. FNAB is the most sensitive and specific method for preoperative assessment of benign and malignant thyroid nodules. Ultrasound-guided FNAB can improve the success rate of sampling and diagnostic accuracy. All patients with DTC should undergo postoperative AJCCTNM staging and low, intermediate and high risk of recurrence stratification to help predict patient prognosis and guide individualized postoperative treatment and follow-up protocols. After DTC surgery, 131I nail clearing therapy was selectively applied. 131I nail clearing therapy is contraindicated during pregnancy, lactation, and planned short-term (6 months) pregnancy. Discontinue levothyroxine (L-T4) for at least 2 weeks or use thTSH to elevate serum TSH to >30 mU/L prior to nail clearing therapy. A low iodine diet (<50ug/d) and avoid iodine-containing contrast agents and medications (e.g., amiodarone) should be used prior to 131I nail clearing therapy. Provide radiation safety instructions to patients prior to 131I nail clearing treatment. 131I dose of 1.11-3.7 GBq for nail clearing treatment in non-high risk DTC patients. Rx-WBS should be performed within 2-10 d after 131I nail clearing treatment. Thyroxine therapy should be started within 24-72h after 131I nail clearing therapy in DTC patients who have stopped thyroxine prior to treatment. For iodine uptake DTC metastases or recurrent lesions, 131I clearing therapy can be applied selectively. For cervical lymph node metastases, 131I 3.7-5.55 GBq is given. 131I is an effective treatment for DTC pulmonary metastases. The common dose of 131I for DTC pulmonary metastases is 5.55-7.4 CBq. Surgical resection is advisable for isolated symptomatic bone metastases. Although 131I is difficult to cure bone metastases, it can improve the quality of patient survival, so 131I treatment is appropriate for bone metastases with iodine uptake. Surgical treatment should be considered first regardless of whether the CNS metastases are iodine ingested or not. All patients with DTC should be treated with TSH suppression after 131I therapy. TSH suppression therapy should be given promptly after 131I treatment according to the risk stratification of patients, with TSH suppression to <0.1 mU/L for patients with intermediate and high risk DTC and 0.1-0.5 mU/L for patients with low risk DTC. The starting dose of L-T4 varies depending on the patient's age and concomitant disease. L-T4 should be administered early in the morning on an empty stomach. Serum TSH should be measured approximately every 4 weeks during dose adjustment. The dose of L-T4 should be increased appropriately during pregnancy according to the increase in gestational weeks, and thyroid hormone and TSH levels should be tested periodically to adjust the dose of L-T4. In pregnant patients with DTC already treated with 131I, TSH suppression levels should be maintained commensurate with the condition. Care should be taken to prevent and treat the appropriate complications during suppression therapy. Female DTC patients avoid pregnancy for 6-12 months after 131I treatment. Contraception for 6 months in males. Establish a 131I treatment isolation area that complies with radiation safety and medical safety to ensure radiation safety of the patient and the surrounding environment. Routine use of MRI and 18F-FDCPET examinations in DTC follow-up is not recommended. In progressive iodine-refractory DTC where conventional therapy has failed, treatment with targeted agents such as sorafenib may be considered.