Postpartum thyroiditis is a type of autoimmune thyroiditis, which clinically manifests as transient or permanent thyroid function abnormality within one year after delivery. The patient’s history of labor and delivery, clinical manifestations, and thyroid function should be taken into account to determine whether postpartum thyroiditis is present. The diagnosis of postpartum thyroiditis is: thyroid function abnormality occurs within one year after delivery, which can be manifested as hyperthyroidism-hypothyroidism biphasic type, hyperthyroidism-monophasic type, and hypothyroidism-monophasic type. There was no prenatal history of abnormal thyroid function. Postpartum Graves’ disease is excluded. The diagnosis of postpartum thyroiditis is made when the above criteria are met. The hyperthyroidism phase of postpartum thyroiditis occurs 1~6 months (usually 3 months) after delivery, manifested by symptoms such as palpitations, fatigue, fear of heat, agitation, etc., and the laboratory examination of T3 and T4 levels will increase, and the iodine uptake rate of the thyroid gland is significantly reduced; the hypothyroidism phase occurs 3~8 months (usually 6 months) after delivery, manifested by symptoms such as fatigue, inattention, constipation, etc., and the laboratory examination of TSH levels gradually increase, and the serum thyroid gland will gradually increase, and the serum thyroid gland will gradually increase, and the serum thyroid gland will gradually increase. The TSH level gradually increases and the serum thyroid hormone level decreases. If postpartum thyroiditis occurs, it is recommended to seek medical advice and standardized treatment under the guidance of a doctor.