Anticoagulation therapy is the key to reducing the disability and mortality rates of atrial fibrillation and improving the quality of life of patients. The key to anticoagulation therapy is to select anticoagulant drugs and decide the intensity of anticoagulation according to the patient’s specific situation. Risk factors for stroke in atrial fibrillation are classified into 3 levels: low risk, intermediate risk and high risk. Low-risk factors include: female, age 65-74 years, coronary artery disease and hyperthyroidism Intermediate-risk factors include: age ≥75 years, heart failure, hypertension, diabetes, left ventricular ejection fraction ≤35% High-risk factors include: history of previous stroke, history of transient ischemia, history of embolic disease, mitral stenosis, post-valve replacement Patients with no risk factors or with only low-risk factors Aspirin 80-300 mg/d only (usually 100 mg/d) Aspirin or warfarin may be used when only 1 intermediate risk factor is present Warfarin is recommended when more than 1 intermediate risk factor or any 1 high risk factor is present. Control the international normalized ratio (INR) at 2.0—3.0 (domestic recommendation 1.8—2.5) when using warfarin. The INR should be maintained at 2.5 or higher in patients after valve replacement.