Objective To evaluate mitral annulus geometry and function in the patients with mitral valve plasty by using real-time three-dimensional transesophageal echocardiography (RT-3D-TEE).Methods RT-3D-TEE was performed in 30 patients with mitral valve plasty.Of them, 10 patients with normal left ventricular end-diastolic dimension (LVDd) (group A), 20 patients with LVDd enlarge (group B), And the mitral annular geometry changes before and after mitral valve plasty were analyzed.Results ①After mitral valve plasty, 2-dimensional area of mitral annulus (A2D), 3-dimensional circumference of mitral annulus (C3D) and anterior-to-posterior diameter of mitral annulus (DAP) were significantly decreased in each group (all P<0.05).And aortic-mitral angle (θ) were no significant differences in each group (all P > 0.05).②Before and after mitral valve plasty, the change trends of anterolateral to posteromedial diameter of annulus (DALPm), annulus height (H), H/DAlPm were significant differences in group A and B.③And the change rate of A2D, C3D, DALPm, DAP, H in group B were more larger than those in group A.Conclusions After mitral valve plasty, some of the mitral annulus structural parameters were significant different.