Abstract： Objective To investigate brain and myocardial danlage in infant with TOF undergoing open heart surgery.Methods Sixty patients with TOF underwent open heart surgery were randomly divided into 2 groups:aortic clamp time≤45rain group and＞45min group.Cardiac electrophysiologic data and inotropic medicine were recorded.Meanwhile serum S-10013,NSE and cTnI before cardiopulmonary bypass,30 min after aortic declamping,12 hours after operation,respectively.Results In aortic clamp time＞45min group,patients Were younger with lower body weight and EF.Heartbeat restoration time is longer,together with higher inotropic medicine dosage,and CK-MB,cTnI,S-1006,NSE at 30 min and 12 hour after aortic declamping.Aortic clamp time was negatively correlated with age,body weight and EF,and positively correlated with heartbeat restoration time,inotropic medicine dosage,CK-MB,cTnI,S-100β,NSE at 30 min and 12 hour after aortic declamping.With adjusted age,body weight and EF,the time of aorta lamp Was positively correlated with inotropic medicine dosage,cTnI,S-100β,NSE at 30 min and 12 hour after aortic declamping.Conclusion Heavy pathogenetic condition and longer time of aorta lamp caused brain and myocardial damag.