There is a possibility of recurrence after thyroid cancer treatment. The specific manifestations of recurrence are not exactly the same, it may be local recurrence or distal metastasis. Local recurrence means enlargement of thyroid gland or neck; distal metastasis means metastatic lesions will appear in lungs and bones, causing corresponding metastatic symptoms.1. Local recurrence: local recurrence of thyroid cancer will have symptoms such as hoarseness, breathlessness, difficulty in swallowing or local pressure pain when the tumor presses on surrounding tissues. When the jugular vein is compressed, patients will have symptoms such as angry veins on the affected side and facial edema; 2. Distal metastasis: new metastases appear in the lung, patients will have symptoms such as hemoptysis, irritating dry cough and chest pain; in addition, some patients with thyroid cancer will have metastasis on the bone, causing bone pain, bone destruction and pathological fracture. Ultrasound is an important examination method to detect thyroid cancer recurrence, and when a neck lump or other symptoms appear, timely assessment of the condition is required for appropriate treatment.