Thyroid cancer is thyroid cancer and Tg is the acronym for thyroglobulin. The safe value of Tg after thyroid cancer surgery is 10 μg/L. Thyroid cancer is a malignant lesion originating from the follicular epithelium of the thyroid gland, which is mainly divided into differentiated, undifferentiated and other types. Among them, differentiated thyroid cancer mainly includes papillary thyroid cancer and follicular thyroid cancer. Thyroglobulin is a macromolecular glycoprotein secreted by the follicular epithelial cells of the thyroid gland, which is one of the tumor markers for differentiated thyroid cancer. After surgery in patients with differentiated thyroid cancer, Tg levels are generally reduced to less than 10 μg/L. Therefore, the safe value is 10 μg/L. The relationship between other types of thyroid cancer and Tg levels is not too strong. Under normal circumstances, the index of thyroglobulin is 5~40 μg/L. In the process of patients’ post-surgical review, if the index is higher than 10 μg/L, it suggests that patients may have metastatic lesions. It is necessary for the patient to further improve the examination program to clarify the patient’s specific situation before treatment.