Atrial fibrillation is a common arrhythmia in clinical practice,and its incidence is increasing year by year.It seriously affects the quality of life and significantly increases the risk of death,stroke,and heart failure.This paper reports a middle-aged and elderly male patient with atrial fibrillation,systemic embolism and left atrial thrombosis,resulting in myocardial infarction,cerebral embolism,lower extremity artery embolism three diseases co-existing,combined antiplatelet and anticoagulant therapy can effectively reduce ischemia and thromboembolism events,but will increase the risk of bleeding.Through the process of initial diagnosis,referral and follow-up,this paper analyzes the evolution of the patient's disease and reviews the relevant literature,which can improve the clinical understanding and diagnosis and treatment level of this disease.