Objective To investigate the clinical significance of thoracoscopy combined with beating-heart technique to provide a certain reference for selecting clinical operation mode.Methods Forty patients with chronic rheumatic mitral stenosis receiving thoracoscopic mitral valve replacement surgery in the cardiothoracic surgery department of our hospital from September 2012 to September 2015 were included in this study and divided into the experimental group(beating-heart group,20 cases) and control group(arrested heart group,20 cases).The operative time,CPB time,enzymology indicators,RI and operative complications were analyzed and compared between the two groups.Results One case in each group died of postoperative low cardiac output syndrome.Other cases successfully completed the operation without serious operative complications such as low cardiac output syndrome,serious cardiac arrhythmia and air embolism.Two groups had no statistically significant difference in the operation time and time of CPB (P＞0.05),but the ICU staying duration had statistical difference between the two groups(P＜0.05).The levels of CK-MB,cTnI,LDH,TNF-α,IL-6,IL-8 and RI were significantly increased in two groups(P＜0.05),while the levels in the experimental group were significantly lower than those in the control group(P＜0.05).Conclusion Thoracoscopic mitral valve replacement operation with beating-heart may have better protection effect on heart and lung than thoracoscopic arrested-heart mitral valve replacement operation.