Atrial fibrillation is one of the most common clinical arrhythmias and poses a greater threat to the health of patients. The incidence of atrial fibrillation increases gradually with age, and is higher in men than in women in all age groups. In fact, many patients have no obvious clinical symptoms and discover that they are in atrial fibrillation by checking their ECG during a physical examination. In this article, we will elaborate on the clinical symptoms that may occur in patients with atrial fibrillation in order to raise the attention of patients and improve the early diagnosis rate. 1, atrial fibrillation caused by abnormal ventricular rate is an important cause of symptoms. In patients with a normal ventricular rate, there may be no obvious clinical manifestations. When the ventricular rate is too fast or too slow, and when it is significantly irregular, clinical symptoms such as palpitations, fatigue, chest tightness, and decreased exercise tolerance may occur. The attack of atrial fibrillation can cause a decrease in atrial function, and the cardiac output can be decreased by 15% or more. The effect of atrial fibrillation on cardiac function is more obvious in people with existing heart disease, such as ventricular hypertrophy and dilatation, heart valve damage, old myocardial infarction, hypertrophic cardiomyopathy, etc., and is often the main cause of triggering and aggravating heart failure. The symptoms of atrial fibrillation in organic heart disease are more severe, and when the ventricular rate is >150 beats/min, it can also induce angina pectoris in patients with coronary artery disease, acute pulmonary edema in patients with mitral stenosis, and acute heart failure in patients with pre-existing cardiac dysfunction. When heart failure coexists with atrial fibrillation, atrial fibrillation is an important risk factor for cardiac death and all-cause mortality. In primary and paroxysmal atrial fibrillation with normal cardiac structure and function, symptoms of panic caused by abnormal ventricular rate may be the main manifestation of atrial fibrillation, while for patients with persistent atrial fibrillation, most of them show reduced exercise tolerance, walking shortness of breath, fatigue, etc. 2. Ventricular arrest caused by atrial fibrillation can lead to blackout and syncope due to insufficient blood supply to the brain. The repeated onset and termination of paroxysmal atrial fibrillation causing sinus quiescence is an important cause of ventricular arrest. When the interval between ventricular arrests exceeds 3 seconds or more, the patient may cause blackout or syncope. Sustained atrial fibrillation with ventricular arrest, which occurs mostly at night, is associated with altered vagal tone or the use of drugs that inhibit atrioventricular conduction. If multiple ventricular arrests of more than 3 seconds occur in the awake state, they may be associated with atrioventricular block and may be accompanied by more pronounced symptoms. If a patient with persistent atrial fibrillation has one or more long intervals of at least 5 seconds, pacing therapy with a pacemaker should be considered to reduce the clinical symptoms associated with the long intervals. 3. Atrial fibrillation complicated by left atrial appendage thrombus is prone to arterial embolism, of which cerebral embolism is the most common, and is an important cause of disability and death. The risk of cerebral embolism is 17 times higher in patients with valvular heart disease combined with atrial fibrillation and 6 times higher in patients with non-valvular heart disease combined with atrial fibrillation; the rate of cerebral embolism caused by atrial fibrillation is as high as 23.5% in people aged 80-90 years. Left atrial appendage thrombosis can occur after 48 hours of AF, and the left auricle is the most common site of thrombus attachment. It takes more than 4 weeks for the function of the left atrium to return to sinus rhythm after persistent atrial fibrillation, during which time there is still a risk of left atrial appendage thrombosis and embolism. In addition, atrial fibrillation can cause difficulty in sleeping and psychological distress, which should be given high priority in clinical practice. Asymptomatic atrial fibrillation should be taken more seriously because it can also lead to serious consequences such as stroke and death as described above.