Atrial fibrillation is a cardiac arrhythmia in which the strongest auscultatory sound is usually in the apical region, which is the location of the tip of the heart below the left nipple. The apical region is the most commonly used site of cardiac auscultation by clinicians for the identification of atrial fibrillation by auscultation. Other sites on both sides of the sternum, the second intercostal space and the third intercostal space on the left side of the sternum can also be auscultated, but the sound of auscultation is weaker compared to the apical region. Atrial fibrillation auscultation will find that the heart rhythm is absolutely uneven and irregular, and the auscultation sound is also uneven in strength and weakness, and when combined with touching the pulse, it will be found that the number of pulse beats per minute is lower than the number of heart beats auscultated, that is, the pulse count is lower than the heart rate. Atrial fibrillation occurs when the patient often feels palpitations, panic, rapid heartbeat, and even chest tightness, dizziness, weakness and other symptoms, for the clinical diagnosis of atrial fibrillation is also based on electrocardiogram and other tests.