Abstract: Objective: To investigate the efficacy of mitral valve replacement (MVR) by continuous suture with the heart beating under cardiopulmonary bypass (CPB) with mild hypothermia by continuous suture.Methods: Ninety-seven cases of rheumatic heart disease were performed MVR by continuous suture with the heart beating under CPB with mild hypothermia.The superior vena cava and inferior vena cava were blocked with the heart beating through the right atrium-septum in operation.The aspirater was augmentated to keep the view clear in operation.two-0 Prolene suture line was designed for continuous suture in MVR.Affiliate operation included 29 cases of De Vega's tricuspid annuloplast and 5 cases of removing atria sinistrum thrombus.Results: After operation,one patient developed perivalvular leakage,which was repaired 28 h after the first operation;And the other patients were discharged on due time.No low cardiac output syndrome,serious cardiac arrhythmias,air embolism or thrombus occurred.The efficacy was satisfactory during the 2-24 month follow-up.Conclusions: MVR by continuous suture with the heart beating under CPB with mild hypothermia may shorten the operation time,and reduce the complications by adopting the myocardial protection method,which approaches the physiology states and proves effective.