Objective: To compare the early and mid-term postoperative changes of left ventricular structure and function beteen mitral repair and replacement in patients with mitral regurgitation. Methods: 100 patients with degenerative mitral regurgitation underwent mitral valve replacement and mitral repair from January 2008 to January 2018 were retrospectively studyed. Of them, 46 patients underwent mitral repair and(repair group) 54 patients underwent mitral valve replacement(replacement group). The results of color Doppler echocardiography before, one week after, 12 months after and 24-36 months after operation were collected. Left atrial diameter(LAD), left ventricular end diastolic diameter(LVEDD) and left ventricular end systolic diameter(LVESD) were selected to evaluate left ventricular structure, fraction shortening(FS)、left ventricular stroke volume( SV )and left ventricular ejection fraction(LVEF) to evaluate left ventricular function. The data were analyzed by SPSS 22.0. Results: In left ventricular structural parameters, LAD, LVEDD and LVESD in mitral repair group and replacement group were significantly improved compared with those before operation(P<0.05). There was no significant difference in LAD, LVEDD and LVESD between the two groups at 12 months after operation(P>0.05). There were significant differences in LAD(42.26 mm vs 47.15 mm), LVEDD(52.97 mm vs 60.18 mm) and LVESD(31.34 mm vs 34.82 mm) between the two groups at 24-36 months of follow-up(P<0.05). Among the left ventricular function indicators, the early and mid-term SV of the two groups were significantly improved compared with that of the preoperative group(P<0.05). LVEF(0.64 vs 0.59、0.64 vs 0.58)was significantly improved in the 12 and 24-36 months after the operation, and FS(36.18% vs 31.47%) was significantly different in the 24-36 months after the operation(P<0.05). Conclusion Mitral repair has high technical requirements and long operation time, but it has obvious advantages over mitral valve replacement in maintaining left ventricular structure and function in the middle and late period after operation.