Objective To study the clinical features and gene mutation of congenital hyperinsulinism (CHI). Methods Clinical data of one newborn infant with CHI were retrospectively analyzed, and relevant literatures were reviewed. Results The infant was admitted at 24 days after birth due to recurrent hypoglycemia. Genetic examination revealed the single heterozygous mutation on ABCC8, which confirmed the diagnosis of CHI. Experimental treatment of Diazoxide was effective. The blood glucose was normal in the follow up. Conclusions The improvement of genetic testing at the soonest can not only helps early diagnosis of CHI, but also guides the long-term clinical management of CHI.