Transesophageal echocardiography (TEE) is a new ultrasound imaging technique that has been widely used in clinical practice to date. The TEE probe is located in the esophagus or the fundus of the stomach and probes the heart from the back of the heart forward, overcoming the limitations of transthoracic echocardiography, and is not affected by emphysema, obesity, or thoracic deformities. The TEE probe can be rotated from 0 to 180 degrees, which allows the sound beam to explore all anatomical structures and hemodynamic status of the heart in 360 degrees, significantly improving the diagnostic accuracy of heart structure, function, and hemodynamics. What are the clinical needs for transesophageal echocardiography? Firstly, it is most widely used in cardiac surgery, including precordial disease and heart valve disease, especially in the evaluation of the morphological structure and function of valvuloplasty and prosthetic valves; secondly, it can evaluate the systolic and diastolic functions of the heart during surgery, serve as a guide for anesthesia and circulatory assist devices, and provide cardiac surgeons with some parameters of cardiac hemodynamics. Thirdly, it can accurately show the potential thrombus in some cardiac patients (including atrial fibrillation, atrial flutter, etc.). The last aspect is the detection of minimally invasive surgical procedures, such as atrial and ventricular septal defect closure.