Background Epicardial fat thickness (EFT) is increasingly recognized as an independent risk factor of the presence, severity, and recurrence of atrial fibrillation (AF). We investigated the associations between EFT and AF prevalence and identified its correlation with other risk factors. Material/Methods A total of 199 participants who underwent coronary angiography and had confirmed coronary artery disease (CAD) were enrolled in this study. The EFT was measured by echocardiography and the association of EFT with other AF risk factors was evaluated by multivariate logistic regression analysis. Results The EFT was significantly higher in patients with comorbidity of AF and CAD than those with CAD alone (6.86±1.96 mm vs 5.91±1.71 mm, P <0.001). Logistic regression analysis indicated that EFT was a predictive factor of the occurrence of AF in CAD, after adjusting for body mass index (BMI), systolic blood pressure (SBP), left circumflex artery (LCX) stenosis, LA diameter, B-type natriuretic peptide (BNP), creatinine (Cr), and blood urea nitrogen (BUN). LA diameter, SBP, and LCX stenosis are also independent risk factors for CAD complicated by AF. Correlation analysis revealed significant positive linear correlations between EFT and BMI ( P <0.01), EFT, and LA diameter ( P <0.05), as well as positive correlations between LA diameter and BNP, Cr, or BUN. Conclusions Epicardial fat thickness is a strong predictor for AF prevalence in patients with CAD, independent of other AF risk factors such as LA diameter, BMI, and SBP, while LA diameter, SBP, and LCX stenosis are also independent AF risk factors for CAD.