Objective To discuss the value that evaluating right ventricular function of patient with mitral stenosis using omni-directional M-mode echocardiograph (OME)during operation. Methods Fifty-five patients with mitral stenosis were received mitral valve replacement.They were divided into 38 cases of mild pulmonary artery hypertension(groupⅠ) and 17 cases of moderate or severe pulmonary artery hypertension(groupⅡ) preoperative. Transesophageal echocardiography was performed during surgery, the pre-and- postoperative peak systolic velocity of tricuspid annulus(Sa) were measured by OME and quantitative tissue velocity imaging.Results Compared with preoperative Sa, postoperative of most leaflets increased (septal and anterior wall of groupⅠ,all of groupⅡ,P<0.05).Sa was negative correlated with pulmonary arterial systolic pressure(PASP)(r=-0.85,P<0.01). The measurements derived from OME correlated well with those from quantitative tissue velocity imaging (P<0.01).Conclusions There is significant clinical value in assessing right ventricular function after mitral valve replacement using OME.