Patients with atrial fibrillation have a high incidence of embolism and are usually selected for anticoagulation with warfarin, which is poorly effective and risky with aspirin therapy. Warfarin belongs to the coumarin class and is an effective drug commonly used clinically for anticoagulation of atrial fibrillation. Warfarin is generally used to prevent thrombosis in atrial fibrillation. When warfarin is taken orally, the International Normalized Ratio of Prothrombin Time (INR) needs to be controlled between 2.0 and 3.0, thus preventing the occurrence of stroke safely and effectively. Contraindications to warfarin are active bleeding, warfarin allergy, severe hepatic and renal insufficiency, etc. Adverse reactions are bleeding, granulocytosis, leukopenia, etc. Occasionally, nausea and vomiting are seen. Aspirin is an antiplatelet drug that is far less effective than warfarin in preventing strokes due to atrial fibrillation, and the risk of bleeding is much higher with aspirin than with warfarin. Contraindications to aspirin are aspirin asthma, peptic ulcer, active bleeding, etc. Adverse reactions are gastrointestinal reactions and occult gastrointestinal bleeding. People with atrial fibrillation should choose the appropriate medication to use under the guidance of a doctor, and once an adverse reaction occurs, they should contact their doctor immediately to adjust their medication.