Abstract： Objective To analysis the change of electrocardiogram(ECG)in the children with congenital ventricular septal defect(VSD)by interventional processes and to explore how to decrease the incidence of serious arrhythmias.Methods To record the ECG before and after interventional closure in the 260 patients that hey were divided into arrhythmia group and no arrhythmia group(control group).The patients were treated with nutrition of cardiac muscle and medicines of reducing the cardiac muscle dropsy when they suffered from complete or serious complete or severe atrioventricuhr block(AVB)even underwent the temporary pacemaker quickly.Results There were 178 csses in control group.82 cuses(31.5%)had arrhythmiag after the interventional,in which 4 cases(1.5%)were complete/serious AVB.36 cases(13.8%)were given medicine above.The age was smaller and the body weigh was less in the arrhythmia group than that of control group(P<0.05).The device occluder was bigger in the arrhythmia group than that of control group(P<0.05.There were significant differences in the comparison of the heart rate,QRS interval,PR interval,QT interval and QTc before and after occlusion in all the cases(P<0.05).Conclusion The changes of ECG have to be taken attention when under-went transcatheter VSD closure using.It is important to avoid the oversized devices.When complete right branch bundle block(CRBBB),complete left branch bundle block(CLBBB)and second AVB occur in the procedure or after that,medicine should be given as early as possible,and once complete/serious AVB has emerged,it is much helpful to perform the temporary pacemaker.All of the cases with arrbythmia should be long-term followed-up.