Abstract Purpose: The purpose of our study was to explore the relationship between EAT thickness and left atrial phasic function in patient with non-valvular atrial fibrillation (NVAF). Methods: 100 NVAF patients were enrolled, including 50 patients with paroxysmal AF and 50 patients with persistent AF. Another 50 patients without AF in sinus rhythm were selected as the control group. EAT thickness in front of the right ventricular free wall was measured using transthoracic echocardiography(TTE) at end-systole, while left atrial phasic function parameters were measured by Real-time three-dimensional echocardiography(RT-3DE) and two-dimensional speckle tacking imaging(2D-STI), including left atrial total emptying fraction(LATEF), left atrial active emptying fraction(LAAEF), left atrial passive emptying fraction(LAPEF), left atrial reservoir strain(LASr), left atrial contraction strain(LASct) and left atrial conduit strain(LAScd). Subsequently, we compared EAT thickness and left atrial phasic function parameters in each group, and analyzed the relationship between EAT thickness and left atrial phasic function parameters. Results: Compared with control group, patients with paroxysmal AF and persistent AF groups had sequentially greater EAT thickness and left atrial diameter (LAD), but sequentially lower left atrial phasic function parameters (LATEF, LAAEF, LAPEF, LASr, LASct, LAScd) (all p<0. 001). By Pearson and Spearman Correlation Coefficient, EAT thickness was significantly positively correlated with LAD and negatively correlated with left atrial phasic function parameters (all p<0. 001). Conclusions: EAT thickness in front of the ventricular free wall measured by TTE was significantly correlated with left atrial phasic function in patients with NVAF, which could effectively reflect the trend of left atrial function changes, thus providing some reference for clinical practice and early intervention of left atrial remodeling.