One recurrence of thyroid cancer will be more serious. Thyroid cancer is clinically divided into four types: papillary thyroid cancer, medullary thyroid cancer, follicular thyroid cancer and undifferentiated thyroid cancer, etc. More than 90% of the patients have the pathological types of papillary thyroid cancer and follicular thyroid cancer, which are relatively slow-growing and have low recurrence rate. When recurrence occurs, it is mostly at the site of the original surgery or lymph nodes in the neck, and it is necessary to judge the site of recurrence. If the recurrence is only small and without local invasion, radioactive iodine 131 can be used to treat papillary thyroid carcinoma and follicular thyroid carcinoma, and the prognosis is still good. On the other hand, medullary carcinoma and undifferentiated carcinoma of the thyroid should be noted because of their higher degree of malignancy, easy recurrence and serious results. For the recurrence of thyroid malignant tumors, it is recommended to consult the thyroid surgery department of regular hospitals and have regular checkups, so as not to be negligent to avoid delaying the condition.