The main feature of atrioventricular block electrocardiogram shows a prolonged PR interval, and electrocardiography is the best test to diagnose this disease. AV block is generally categorized into three degrees, and their respective ECG features are as follows: 1. First-degree atrioventricular block: conduction from atria to ventricles is delayed but not interrupted. The ECG shows a prolonged PR interval, usually >200ms, and each P wave is followed by a QRS wave. 2. Second-degree AV block: intermittent AV block, categorized into second-degree Mohs’ type I and Mohs’ type II. Electrocardiogram (ECG) shows (1) second-degree Mohs’ type I, with progressive prolongation of the PR interval for multiple beats until a P-wave off; (2) Mohs’ type II, with prolongation of the PR interval, but it remains unchanged until a P-wave is off. 3. Third-degree atrioventricular block: complete atrioventricular block, in which atrial excitation cannot be transmitted to the ventricle, the PR interval is not fixed, and the electrocardiogram shows that the P-wave and QRS-wave activities are independent of each other and have no correlation. If weakness, dizziness, angina pectoris and other symptoms, you should be alerted, and it is recommended to consult the doctor in time, and improve the relevant examination if necessary.