According to the size of thyroid tumors, primary thyroid tumors can be divided into four stages: T1, T2, T3 and T4. Among them, T1 is less than or equal to 2cm, T2 is between 2-4cm, T3 is more than 4cm, and T4 has exceeded the thyroid envelope. 1. T1 stage of thyroid tumor: the maximum diameter of thyroid tumor at this stage is less than or equal to 2cm, and its scope is limited to the thyroid peritoneum. 2. T2 stage of thyroid tumor: the maximum diameter of thyroid tumor in this stage is more than 2cm and less than or equal to 4cm, and its scope is limited to the thyroid peritoneum. 3. Thyroid tumor T3 stage: the maximum diameter of thyroid tumor in this stage is more than 4cm, which may be confined within the thyroid peritoneum or may invade the peripheral tissues of the thyroid gland. 4. Thyroid tumor T4 stage: at this stage, the thyroid tumor has exceeded the thyroid peritoneum and started to invade subcutaneous tissues, trachea, encircling carotid artery, and laryngeal reentrant nerve. If thyroid occupying lesions are found through imaging examination, other examinations should be completed in time to clarify the diagnosis and carry out targeted treatment as early as possible.