Neonatal hypoglycemia refers to the blood glucose lower than the minimum blood glucose value of normal newborns caused by various reasons. At present, the diagnosis of hypoglycemia is mostly made by whole blood glucose lower than 2.2mmol/L at home and abroad, and lower than 2.6mmol/L as the threshold value that needs clinical treatment. Since neonatal hypoglycemia can cause brain damage, it is important to pay attention to it. Generally, the damage to the brain tissue depends on the severity and duration of hypoglycemia, so the baby should be treated promptly when hypoglycemia occurs to avoid persistent hypoglycemia. Otherwise, it may lead to brain cell damage and irreversible brain damage in children. Neonatal hypoglycemia can be divided into two types: transient and persistent. The causes of transient hypoglycemia are related to reduced sugar production, insufficient glycogen storage, excessive consumption and transient insulin excess; persistent hypoglycemia is related to congenital metabolic defects and islet cell hyperplasia. Most children with hypoglycemia lack typical clinical symptoms or are concealed by other diseases. The clinical manifestation of hypoglycemia varies according to the degree of hypoglycemia. The clinical manifestation of the same hypoglycemia level also varies greatly. A few of the symptomatic ones can be clinically manifested as: paroxysmal cyanosis, feeding difficulties, drowsiness, apnea, cyanosis, abnormal crying, trembling, tremor, and even convulsions. Some present with excessive sweating, pale skin and hyporesponsiveness. Most of them occur within a few hours to a week after birth, and the symptoms disappear and blood sugar returns to normal after sugar supplementation.