Objective To investigate the value of transesophageal three-dimensional echocardiography (RT3D-TEE) in the measurement of left atrial appendage flow velocity (PEV) and the rateof three-dimensional volumetric change (3D-EF) in the prediction of spontaneous echo contrastand thrombosis of left atrial appendage in patients with nonvalvular atrial fibrillation. Methods A total of 203 patients with atrial fibrillation were selected and divided into the groups with abnormality and no abnormality. The left atrial appendage flow velocity and the rate of three-dimensional volumetric change were measured, respectively. Results There were significant differences in left atrial appendage flow velocity and the rate of three-dimensional volumetric change between the two groups. The sensitivity predicted by 38% of the 3D-EF cutoff value of the left atrial appendage spontaneous echo contrast or (and) thrombosis was 100%, and the specificity was 90.6%. The sensitivity predicted by30.85 cm/s of the PEV cutoff value of the left atrial appendage spontaneous echo contrast or (and) thrombosis was 100% and the specificity was 89%. Conclusion Real-time three-dimensional transesophageal echocardiography has important clinical value in predicting left atrial appendage spontaneous echo contrastor (and) thrombosis.