Congenital hypothyroidism refers to hypothyroidism that occurs in newborns after birth. According to the location of the lesion, we can classify it into primary and secondary, and according to the final course of the disease, we can classify it into persistent and transient. The primary hypothyroidism is caused by the disease of the thyroid gland itself, which is characterized by elevated TSH and decreased thyroid hormone, and congenital abnormalities of the thyroid gland are the most common cause. Secondary hypothyroidism, also known as central hypothyroidism, is characterized by decreased thyroid hormones and normal or decreased TSH, and is less common. Persistent hypothyroidism is a persistent deficiency of thyroid hormones that requires lifelong replacement therapy in children. Transient hypothyroidism refers to children born with a temporary lack of thyroid hormone secretion due to various reasons, such as the mother or the newborn, and whose thyroid function can be restored to normal. The causes of temporary hypothyroidism are usually the use of antithyroid drugs by the mother, premature birth, low birth weight, iodine deficiency or excess iodine in the mother or newborn. It is important to emphasize that overdose of antithyroid medication in the mother may lead to hypothyroidism in the newborn, but more often than not, the mother’s hyperthyroidism is uncontrolled or poorly controlled, and the newborn may become either hyperthyroid or hypothyroid, and the incidence of hypothyroidism in the newborn is higher than that of hyperthyroidism in such cases. Congenital hypothyroidism is one of the common pediatric endocrine disorders that cause mental and physical developmental delays in children, with serious consequences. However, it is a preventable and treatable disease. Since children with congenital hypothyroidism may have no specific clinical symptoms or mild symptoms in the neonatal period, such as just non-specific symptoms such as little crying, drowsiness, poor suction power, and unremitting neonatal jaundice, screening of newborns is the main method for early detection of congenital hypothyroidism. It is important to emphasize here that our screening time for neonatal hypothyroidism is 72 hours after birth, because after birth, the normal fetus has incomplete hormonal regulation and its thyroid function is manifested by elevated TSH and elevated thyroid hormones in order to adapt to the lower ambient temperature around it relative to the mother’s uterus, and this physiological abnormal state usually recovers after 72 hours, so we choose to Screening is performed after 72 hours after birth. For the treatment of congenital hypothyroidism, the main treatment is thyroid hormone supplementation, and levothyroxine tablets are preferred. However, parents often think that children are so young that they do not need to take a very small dose of medication, which is a complete misconception. On the contrary, the younger the child, the greater the amount of thyroid hormone. For persistent hypothyroidism, lifelong medication is required. The dose of medication varies by age and should be adjusted according to the results of thyroid function tests. For transient hypothyroidism, treatment is generally not required, but we recommend treatment if TSH >10mIU/l is continuously monitored. Since thyroid hormone deficiency after 3 years of age has less impact on mental development, we can stop the medication after 3 years of age for 6 weeks for observation, and then recheck the thyroid function to finally determine whether to continue the medication for children with temporary hypothyroidism or children who are not sure if the hypothyroidism is persistent.