(1) Subacute granulomatous thyroiditis is generally considered to be caused by viral infection. It is usually seen in middle-aged women and typically follows the course of hyperthyroidism, hypothyroidism and recovery of function. The clinical diagnosis is based on enlargement of the thyroid gland, pain, tenderness, with systemic symptoms and high serum FT3.FT4.raw and decreased iodine 131 uptake rate of the thyroid gland and increased blood sedimentation. Hashimoto’s thyroiditis can also be associated with mild thyroid pain and tenderness, but it is less common. The clinical picture can be based on the absence of obvious disorders of iodine metabolism and increased sedimentation in Hashimoto’s thyroiditis. The thyroglobulin antibodies TgAB, TPOAB and TMAB titers are significantly elevated to differentiate from this disease. (2) Subacute lymphoid thyroiditis, also known as painless thyroiditis, can be distinguished between disseminated and postpartum types. Recent studies have found that its development may be related to an autoimmune response. The main manifestation is hyperthyroidism, which usually lasts less than 3 months and is typically followed by a transient hypothyroid phase, and rarely becomes permanent. The best way to differentiate subacute lymphoblastic thyroiditis from hyperthyroidism is to determine the iodine uptake rate of the thyroid gland, which is significantly decreased in the former and significantly increased in the latter, separated from the serum thyroxine concentration, i.e., the serum thyroid concentration is increased and the iodine uptake rate is very low. Hashimoto’s hyperthyroidism is also known as hyperthyroidism, but the iodine uptake rate is often at or above normal and the symptoms of hyperthyroidism rarely resolve on their own.