Objective:To investigate the relationship between indicators of carotid atherosclerosis and onset of ischemic stroke in patients with non-valvular atrial fibrillation (NVAF).Methods:This is a case-control study, a total of 397 NVAF patients with newly diagnosed ischemic stroke (case group) and 3 038 NVAF patients without ischemic stroke (control group) from January 2015 to December 2017 were included in the study. Differences in general clinical features and carotid atherosclerosis indexes between the two groups were compared. Univariate and multivariate logistic regressions were used to analyze the correlation between carotid atherosclerosis indexes and ischemic stroke.Results:Proportions of patients with carotid intima thickening, carotid plaque, stable plaque, unstable plaque, and moderate to severe stenosis were higher in the ischemic stroke group than those in the control group (82.1% vs. 64.4%, 69.3% vs. 50.3%, 43.6% vs. 30.6%, 25.7% vs. 19.7%, and 7.3% vs. 4.0%, respectively, all P <0.05). After adjustment of age, gender, heart failure, hypertension, low density lipoprotein -cholesterol and drug use, multivariate analyses showed that subjects with carotid intima thickening, carotid plaque, stable plaque, unstable plaque, moderate to severe stenosis had 1.766, 2.111, 1.892, 2.256 and 1.824 times the risk for the development of ischemic stroke compared with the subjects without any carotid atherosclerosis indicators. Conclusion:Carotid atherosclerosis, especially with unstable carotid plaque, is associated with ischemic stroke in patients with NVAF.