Atrial fibrillation in middle-aged and old people should be examined by physical examination and auxiliary examination, which includes electrocardiogram, cardiac ultrasound, thyroid examination, electrophysiological examination and so on. 1. Physical examination: usually counting the heartbeat and feeling the pulse can help to detect the signs of atrial fibrillation at an early stage; if there is absolute arrhythmia and the first heart sound is not equal in strength, it suggests the existence of atrial fibrillation. 2. Auxiliary examination. Electrocardiogram (ECG): The diagnosis of atrial fibrillation must be based on at least one lead of the ECG recording of arrhythmia episodes. Electrocardiogram can clarify the heart rhythm and confirm the existence of atrial fibrillation. Cardiac ultrasound: to clarify the size and function of the atria and ventricles, the presence of valvular heart disease, and pulmonary artery pressure. Thyroid function test: If the first episode of atrial fibrillation, the ventricular rate is not easy to control, or if the atrial fibrillation recurs after the heart rhythm is restored, the thyroid function should be clarified. Electrophysiology: To elucidate the mechanism of the arrhythmia and to search for therapeutic ablation sites or atrioventricular conduction block/modification sites. Atrial fibrillation in middle-aged and old people should be under the guidance of the doctor, combined with the patient’s condition to improve the relevant examination, in order to systematic treatment under the guidance of the doctor.