Objective To evaluate the effects of different degrees of left atrial low voltage on left atrial structure，function and clinical characteristics in patients with non-valvular atrial fibrillation （AF）. Methods Sixty-six patients with AF who underwent radiofrequency ablation were enrolled. Clinical data of patients were recorded before operation. Transthoracic echocardiography were performed to obtain the left atrial end-systolic diameter, left atrial end-systolic diameter, left ventricular end-diastolic diameter, left ventricular ejection fraction (LVEF), and the ratio of early diastolic peak mitral flow to peak mitral annular velocity （E/ e ''）.The Left atrial reservoir phase strain (LASr), pipeline phase strain (LAScd), pump functional phase strain (LASct) and left atrial ejection fraction （LAEF） were collected by three-dimensional speckle tracking imaging technique. Left atrial low voltage area was obtained by three-dimensional electro-anatomical mapping during radiofrequency ablation. According to the percentage of low voltage area to left atrial surface area，the patients were divided into non-low voltage group（group I），the degree of left atrial LVA ＜ 10%（group II），and the degree of left atrial LVA ≥10%（group III）, 29 cases, 26 cases and 11 cases, respectively. The above parameters among the three groups were compared. The correlation between left atrial strain parameters and left atrial low voltage area was analyzed. Results The CHA2DS2-VASc score and the cerebral infarction or transient cerebral ischemia history in group Ⅲ were higher than those in group Ⅰ and group Ⅱ, and the differences were statistically significant（P＜0.05）. There were statistically significant differences in the proportion of E/e ''＞14 between group Ⅰ and group Ⅲ, group Ⅱ and group Ⅲ （P＜0.05）. There were no significant differences in left atrial and left ventricular size parameters and LVEF among the groups. LASr, LAScd, LASct and LAEF in group Ⅲ were lower than those in group Ⅰ and group Ⅱ, and the differences were statistically significant （P＜0.05）. There was no significant difference in left atrial strain parameters and LAEF between group Ⅰ and group Ⅱ. Correlation analysis showed that LASr, LAScd, LASct were negatively correlated with left atrial low voltage area. Correlation analysis showed that there was a significant correlation between the left atrial low voltage area and left atrial strain parameters（r=-0.538、-0.448、-0.501,P＜0.05）. Conclusion When the degree of LVA reaches 10%, the left atrial structure does not change, but its function is reduced and the incidence of stroke increases. Three-dimensional speckle tracking imaging technique can early detect the effect of left atrial low voltage on left atrial function in patients with nonvalvular atrial fibrillation.