Abstract： Objective To investigate the value of transesophageal echocardiography guided occluded operation for ventricular septal defects(VSD)through the lower ministernotomy.Methods Total 20 patients with perimembranous VSD were in the study.VSD patients(20 cases)were given preoperative transthoracic echocardiography.Under general anesthesia,the patients who were meeting the blocking condition had the transesophageal echocardiograph.The size of occluder was decided according to the diameters of VSD.During operation,ultrasound was applied to monitor the procedure of occlusion and to evaluate if there were peripheral residual shunts around the occlusion and other complications.Results The occluded operations of 20 VSD patients were performed successfully.Conclusions Transesophageal echocardiography,as a safe and simple method,plays an important role in selecting patients and determining the size of the occluder correctly before occlusion operation.It guides the placement of the occluder in operation and evaluates the effect of operation.