Post-operative review once in 3-6 months. Regular review is required after thyroid cancer surgery in order to detect any recurrence and metastasis in time, usually once in 3-6 months. The examination items include blood test for thyroid function and HTg, ultrasound of the thyroid gland in the neck, ultrasound of the abdomen, chest X-ray, etc. Depending on the situation, CT and MRI of the neck can be performed, and if possible, PET-CT can be performed. If HTg is significantly higher than normal, be alert for recurrence. The recurrence rate of thyroid cancer in children is relatively more prone to recurrence, which is related to the surgical standard and the malignancy of the tumor. If the tumor is highly malignant, the recurrence rate is high, and if it is less malignant, the recurrence rate is also relatively low. Generally speaking, the recurrence rate of differentiated thyroid cancer is less than 10% after standardized treatment. Regular postoperative review helps to detect any tumor recurrence and metastasis in time. When HTg is significantly higher than normal, it indicates the possibility of local recurrence and metastasis; if a lump reappears in the neck surgery area, relevant examination should be performed to exclude the recurrence of local primary site and regional lymphatic drainage metastasis site. The treatment of recurrent tumor is much more complicated than the first one, which requires comprehensive consideration of the child’s physical condition, recurrence site and involved organs.