Objective To investigate the value of transesophageal echocardiography（TEE） in surgery of acute Stanford type A aortic dissection（AAD）. Methods There were forty-one patients diagnosed as AAD by aortic computed tomography angiography in our research. Before aortic surgery，aortic root information can be diagnosed with TEE which was benefit in determining operation strategy. After TEE, patients are divided into three groups according to dissection scope and severity. Group A∶16 cases, AAD without dissection involving aortic root. Group B∶9 cases, AAD with mild to moderate dissection of aortic root. Group C∶16 cases, AAD with severe dissection of aortic root. Pre-operation TEE examine aortic root form，dissection scope，pattern and function of aortic valve. Diameter of aortic annulus, aortic sinus, the junction of the aortic sinus and displayable ascending aorta were measured and compared in each group with different parameters. In addition，TEE can be used to observe the clinical effect immediately after the surgery. Results All of 41 patients showed dissection in their ascending aorta using pre-operation TEE with the positive rate being 100%.No statistically significant differences in diameter of aortic annulus was found among group A,B and C. Diameter of aortic sinus of group B and C were significantly higher than those group A. Coronary arterial dissections can be checked out in operation in the some patients. The sensitivity of TEE was 56% and accuracy was 62.5%.Post-operation TEE can evaluate function of the artificial aortic valve or repaired aortic valve. And the artificial blood vessel and coronary artery anastomosis also can be checked by TEE. Conclusion Pre-operation TEE can assess aortic root helping to determine operation strategy and post-operation TEE can?evaluate the clinical effect immediately after the surgery.