This paper reported a case of congenital hyperinsulinism and reviewed the relevant literatures regarding to the etiology, pathogenesis, clinical and pathological features, diagnosis and treatment of this disorder. The baby (male), with gestational age of 36 weeks and birth weight 4 200 g, was delivered by caesarean section. It presented with hypoglycemia immediately after birth (0.8 mmol/L). Through the course of the disease, the baby's blood sugar manifested with 1.2-2.8 mmol/L although glucocorticoid was administered. 10% glucose solutions were intravenously infused at a speed of 10-17 mg/(kg·min)for this patient to retain a stable blood sugar level. The plasma insulin level was 24.13 U/L and blood sugar level was 1.5 mmol/L on day 30 of his life. The ratio of plasma insulin (U/L)and plasma glucose (mg/dL) was 0.89. These results suggest an inappropriate insulin secretion resulting in persistent hypoglycemia in this baby and so it was definitely diagnosed with congenital hyperinsulinism.