Abstract: AIM To observe and analyze the relationship between third-degree atrioventricular block of acute myocardial infarction (AMI) patients and blood supply of atrioventricular node artery. METHODS Acute myocardial infarction candidate patients, according to whether or not there was a concurrent degree of atrioventricular block (AVB) III, were divided into two groups. One group underwent acute myocardial infarction and third-degree atrioventricular block (n=35). The other group underwent acute myocardial infarction but without third-degree atrioventricular block (n=215). The origin of the atrioventricular node blood supply, the probability of the third-degree atrioventricular block of different sources of the artery of the atrioventricular node, and recovery time of third-degree atrioventricular block in restorative blood flow were compared. RESULTS The origin of the atrioventricular node artery blood is the descending artery of the right coronary artery and Kugel’s artery of the left circumflex. In the case group, the origin of the atrioventricular node artery blood is only from the descending artery of the right coronary artery or Kugel’s artery of the left circumflex, in which the right coronary artery was more than the left circumflex, but not the left anterior descending artery (P<0.01). When the infarction-related artery was reperfusioned and restored the blood supply, AVB returned to sinus rhythm. CONCLUSION AVB III is related to the interruption of the atrioventricular node artery. After recovery of the atrioventricular node artery blood, AVB III returns to sinus rhythm.