Postpartum thyroiditis is a subacute autoimmune system thyroid disease that occurs after delivery or abortion. It is a specific type of autoimmune thyroiditis and is the main cause of abnormal maternal thyroid function and is not a physical or bacterial inflammation that requires the application of antibacterial medication. It is called postpartum thyroiditis because it occurs after childbirth. Its postpartum incidence is 5-10% and can occur within 1 year after delivery, mostly between 1 and 7 months after delivery. When a woman is pregnant, her immune function is suppressed, and when the baby is delivered from the mother, the suppressed immune function of the maternal organism will return to normal, and during the recovery process the maternal immune function may become transiently dysfunctional, with a temporary increase in immune response. Most of the postpartum thyroiditis is accompanied by mild enlargement of the thyroid gland without pain, along with thyroid dysfunction, the disease can go through three stages: 1. The clinical symptoms may include swelling of the face, fear of cold, drowsiness, memory loss, increased menstrual flow, weight gain and other metabolic depression; 3, recovery period: after self-repair, thyroid function returns to normal, and the symptoms can be relieved naturally, but in 20% of cases, the hypothyroidism cannot return to normal and develops into permanent hypothyroidism. Most patients come to the clinic during the hypothyroidism phase, and a few come to the clinic during the hyperthyroidism phase. Not all cases have all three phases of manifestations, with about 26% having all three phases, 38% having only hyperthyroidism, and 36% having only hypothyroidism. The prognosis of postpartum thyroiditis is good, the course of the disease is self-limiting, most of them can remit on their own, the patients mostly return to normal within one year after delivery, only a few individual cases turn into permanent hypothyroidism, generally without comorbidities and sequelae, but 25-40% of patients have another pregnancy, the possibility of recurrence of postpartum thyroiditis after delivery is high. Current research suggests that postpartum thyroiditis is associated with iodine overdose, and it is believed that patients with postpartum thyroiditis who develop hypothyroid hormoneemia during pregnancy will affect the fetus’ neurological development, leading to mental retardation in the child. Postpartum thyroiditis generally does not require special treatment, and if the condition is mild and the symptoms are not obvious, it may not be treated. If the symptoms are obviously accompanied by hyperthyroidism, symptomatic treatment such as beta-blockers can be used, in addition to avoid blindly taking anti-thyroid drugs, iodine 131 or thyroidectomy and other treatments, but also long-term follow-up. If symptoms are obviously accompanied by hypothyroidism, thyroxine tablets should be supplemented and thyroid function should be monitored regularly. For those who turn into permanent hypothyroidism, long-term levothyroxine replacement therapy is required.