Objective To discuss the feasibility,safety and surgical effect of the modified Prolene thread double-headed needle"U-shaped"suture combined with extra-and intracavity combination knotting method in thoracoscopic diaphragm plication in the treatment of diaphragmatic eventration in infants.Methods A retrospective analysis was conducted on clinical data of 70 infants who underwent thoracoscopic diaphragm plication in the treatment of diaphragmatic eventration in our hospital from May 2010 to May 2022.According to the different methods of suturing and knotting,the patients were divided into the improved group(modified Prolene thread double-headed needle"U-shaped"suture combined with extra-and intracavity combination knotting method,n =30)and the conventional group(intracavity suture knotting method,n = 40).The perioperative indicators,as well as whether there was knot loosening or recurrence of diaphragmatic eventration,were compared between the two groups.Results All the 70 operations were performed safely and successfully,without conversion to open surgery.The operation time in the improved group was significantly less than that in the conventional group[(35.3±7.4)min vs.(64.7±10.8)min,t =13.521,P =0.000].There were no statistically significant differences between the two groups in terms of intraoperative bleeding volume,indwelling time of thoracic drainage tube,postoperative hospital stay,preoperative,intraoperative,and postoperative pH values,PO2,and PCO2 in arterial blood gas,and postoperative slight diaphragm elevation(P>0.05).All the 70 cases were followed up for 6-24 months postoperatively,with a median follow-up time of 12 months,having no knot loosening or recurrence of diaphragmatic eventration.No death was reported.Conclusions The modified Prolene thread double-headed needle"U-shaped"suture combined with extra-and intracavity combination knotting method in thoracoscopic diaphragm plication in the treatment of diaphragmatic eventration in infants is safe,feasible,effective,and easy to operate.Doctors with a certain endoscopic surgery experience can master it quickly,which is suitable for promotion in qualified hospitals.