Atrioventricular block is a blockage of impulses during atrioventricular conduction. There are two types of block: incomplete and complete. The former includes first- and second-degree AV block, while the latter is also called third-degree AV block, and the block can be in the atrium, AV node, Hitchcock’s bundle and double bundle branches. In complete AV block, the temporal relationship between the atria and the ventricles is separated, and the atria lose their auxiliary pumping effect on ventricular contraction, resulting in a decrease in cardiac output. The diagnosis is not difficult to make based on the typical ECG changes and combined with the clinical presentation. In order to estimate the prognosis and determine the treatment, it is still necessary to distinguish between physiological and pathological AV block, block above the branches of the AV bundle and triple branch block, and the degree of block. 1.According to medical history, clinical symptoms and signs. 2.Diagnostic criteria of electrocardiogram (1) Look for complete atrioventricular block in complete atrioventricular disconnections. (2) According to the frequency of P (P′, F, f) wave, the appearance of the time phase and QRS morphology, time and frequency for comparison, P is not related to QRS, ventricular rate <60 times/min, preliminary identification of complete atrioventricular disjunction is blocking, there is interference, or blocking and interference coexist, whether interference is dominant, or blocking is dominant. Most P waves located after the T wave to a certain time after the next P wave still can not be transmitted down, can confirm the diagnosis of complete atrioventricular block.