〔Abstract〕 ObjectiveTo explore the effect of transesophageal echocardiography (TEE) on the evaluation of left atrial appendage (LAA) structure and function in patients with atrial fi brillation. Methods 60 patients with atrial fi brillation who were admitted to Shenzhen people's hospital from February 2017 to February 2020 were selected as the observation group. At the same time, 60 healthy volunteers were randomly selected as controls in the hospital during the same period. In the group, transesophageal echocardiography was performed on both groups, the morphological structure of the LAA was observed, various parameters of the LAA were measured, and their functions were evaluated. Results The left atrial appendage structure of the observation group showed mostly 2 or 3 lobes. The control group was dominated by 2 lobes, followed by single-lobe. The composition ratio of 3 lobes LAA in observation group was higher than that in control group, and the difference was statistically signifi cant (P < 0.05); the LAA ejection fraction (LAA–EF), LAA peak blood fl ow emptying velocity (LAA–PEV) of the observation group were lower than thecontrol group. The LAA orifi ce area index (LAA–OI), the LAA minimum volume index (LAA–VImin), and the left atrial appendage maximum volume index (LAA–VImax) were all higher than the control group, and the differences were statistically significant (P < 0.05). Conclusion For patients with atrial fi brillation, it is highly feasible to use TEE to evaluate the structure and function of the LAA. Through quantitative analysis of the function of the LAA, the evaluation of the patient's risk of thrombosis has a high guiding value for the formulation of clinical management protocol.