Abstract: OBJECTIVE To evaluate the safety and efficacy of different doses of warfarin anticoagulation therapy in non-valvular atrial fibrillation, and risk factors associated with ischemic stroke. METHODS A total of 130 patients with non-valvular atrial fibrillation from January 2012 to December 2013 were selected. patients were divided into group A with moderate intensity warfarin anticoagulation, international normalized ratio (INR) was controlled at 2.0 to 3.0, group B with low intensity warfarin anticoagulation, INR was controlled in the 1.6 to 2.0. Adverse reactions and ischemic stroke risk in two groups of patients were recorded during follow-up. INR in diagnosis of anticoagulant bleeding risk was analyzed by using ROC curve. Risk factors associated with ischemic stroke were analyzed by multivariate Logistic regression analysis. RESULTS The ischemic stroke, transient ischemic attack, peripheral arterial embolism incidence in group A was 6.70%, 3.45%, 1.72%, while it was 8.33%, 4.17%, 4.17% in the group B, the difference was not statistically significance (P>0.05). The dosage of warfarin, INR value and the incidence of bleeding in group A were (3.13±0.45)mg·d^-1, (2.61±0.32), and 24.14%, respectively, and The dosage of warfarin, INR value and the incidence of bleeding in group B were (2.63±0.32)mg·d^-1 (1.84±0.30) and 9.72% respectively. the area under the ROC curve was 0.858(95%CI: 0.791-0.924), INR's cut-off value was 2.85, sensitive and specificity in this value judgment of bleeding risk was 81.1% and 67.2%. Multivariate logistic regression analysis showed that age, hypertension, diabetes, heart failure, history of stroke, INR, TTR (time in therapeutic range), stroke risk score were independent risk factors in patients with non-valvular atrial fibrillation occurrence of ischemic stroke (P<0.05). CONCLUSION Warfarin at low or moderate doses can both prevent ischemic stroke in patients with non-valvular atrial fibrillation, and patients with risk factors associated with ischemic stroke should be treated with warfarin as early as possible. Monitoring of INR is effective to prevent possible bleeding.