Sudden onset of syncope without any signs is often indicative of possible secondary heart disease. However, this condition is very rare in children. In arrhythmias, syncope can occur due to a sudden drop in cardiac output, resulting in insufficient blood supply to the brain. In bradycardia, syncope can occur when the cardiac output decreases because the heart rate decreases, or in tachycardia, when the heart does not have enough filling time due to a shortened diastolic period. Cardiogenic syncope mainly includes sinus node dysfunction, AV block, congenital long QT syndrome, supraventricular tachycardia, ventricular tachycardia, hypertrophic obstructive cardiomyopathy, aortic stenosis and primary pulmonary hypertension. According to our study of the clinical features of 23 children with syncope as the chief complaint of cardiogenic syncope, the incidence of ECG abnormalities and exertion-induced syncope were the highest in children with cardiogenic syncope, accounting for 91.7% and 60.9% of the cases, respectively, so children with these two clinical features should be highly suspected of having cardiogenic syncope and should be further evaluated cardiologically. Further cardiac evaluation should be performed.