Swollen lymph nodes one year after thyroid cancer surgery means that the lymph nodes appear enlarged about one year after thyroid cancer surgery. Patients should not worry too much when lymph nodes are enlarged one year after thyroid cancer surgery, it does not mean that it is caused by recurrence or metastasis of thyroid cancer, but may be caused by reactive hyperplasia of lymph nodes or obstruction of lymphatic reflux due to the ligation of lymphatic channels during surgery. Thyroid cancer includes papillary, follicular and medullary carcinoma and undifferentiated carcinoma, among which most of the undifferentiated carcinoma, papillary carcinoma and follicular carcinoma can be cured through aggressive radical surgical treatment and lymph node dissection treatment, and seldom recurrence and metastasis occur after surgery. On the other hand, medullary thyroid cancer is more malignant, and metastatic recurrence may occur after surgery. When the lymph nodes are enlarged one year after thyroid cancer surgery, patients should be examined in regular hospitals and under the guidance of professional doctors in time to clarify the specific reasons.