Abstract： Objective To study the the feasibility of real-time 3D transesophageal echocardiography (RT-3D TEE) to measure the distance between the coronary ostial and the junction of left ventricle and artery.Methods The RT-3D TEE image of the aortic root was collected intraoperative in 65 cases who were refered to our center for valve replacement.The reconstruction of the aortic annulus was done in the QLAB quantitative analysis software and the height parameter of the annulus could be generated.Meanwhile the coronary artery position was observed and the distance between the coronary ostial and the junction of left ventricle and artery was measured respectively.Results In the 65 cases,49 cases clearly showed bilateral coronary ostial,three cases only showed the left coronary ostial,six cases only showed the right coronary ostial,seven cases of both sides of the coronary ostial were unclear.The shows rate of right coronary ostial was 84.61％ (55/65),with the left coronary ostial 81.54％ (52/65).The measured value of the L-AA in systole and diastole were (15.5 ± 1.9)mm,(12.8 ± 1.5)mm,the R-AA systole and diastole measured values were (13.7 ± 1.8)mm,(12.4 ± 1.7)mm,respectively,there was significant difference between systole and diastole respectively.The aortic annulus height (H) got by 3D reconstruction of the aortic annulus was lower than ventricular-arterial junction to the coronary artery distance in both systole and diastole.Conclusions Not only can RT-3D TEE reconstruct the annulus,but also can show and measure the distance between the coronary ostial and the junction of left ventricle and artery respectively.