To observe the correlation between nonvalvular atrial fibrillation and carotid atherosclerosis for high risk group of stroke and its TCM Syndrome distribution. Methods:A total of 5999 patients of high risk group of stroke were divided into atrial fibrillation group and nonatrial fibrillation group. Carotid artery ultrasound was applied to observe the intima mediathickness(IMT) and atherosclerotic plaque. To observe the distribution of TCM syndrome elements in the two groups. Results:The detection rate of smoking and dyslipidemia in atrial fibrillation group was higher than nonatrial fibrillation group, and the difference was statistically significant(P<0.05). Compared with nonatrial fibrillation group, the occurrence rates of IMT and atherosclerotic plaque in atrial fibrillation group were significantly higher(P<0.05). Logistic multifactor regression analysis showed that atrial fibrillation, hypertension, smoking, eating habits, family history of stroke, lack of physical exercise were associated with IMT of carotid artery. There was no significant difference in TCM syndrome elements between the two groups(P>0.05). Conclusion:In the high risk group of stroke, smoking and dyslipidemia are independent risk factor for carotid atherosclerosis and plaque formation. Carotid artery intima and plaque formation in the atrial fibrillation group was higher.The major syndrome elements of atrial fibrillation group are phlegm dampness and wind. While atrial fibrillation has no effects on the types and distribution of TCM syndrome elements．