Objective To investigate the risk factors of electrical storm(ES) in patients with acute myocardial infarction (AMI) during perioperative period of direct percutaneous coronary intervention(PCI).Methods Forty-one AMI patients had been treated with direct PCI.The patients with perioperative ES were included in ES group and those without perioperative ES were included in conntrol group.ES was defined as the occurrence of spontaneous ventricular tachycardia or venicular fibrillation was twice or more within 24 h and unable to stop by itself and emergency treatment was needed.The difference of the clinical data between two groups were compared.Results There were 7 in 41 patients with direct PCI who had ES,the incidence was 17.07％,and 34 cases didn't have ES.Systolic pressure,diastolic pressure,white cell count,blood glucose,international normalized ratio and time duration from chest pain onset to direct PCI between two groups had no significant differences (P ＞0.05).Age,CK-MB,cardiac troponin I,the diameter of infarctrelated arleries(IRA ),incidence of reperfusion arrhythmia and mortality of ES group were all obviously higher than those of control group (P ＜ 0.05 or ＜ 0.01 ).The incidence of ES in patients whose IRA was left main artery or occlusion of middle section of two main coronary arteries,right coronary artery,left anterior descending branch and left circumflex artery was 66.67％(2/3),18.75％(3/16),11.76％(2/17) and O, respectively.Conclusions Perioperative ES during direct PCI most commonly occurrs in AMI patients with left main artery or occlusion of middle section of two main coronary artery.The diameter of IRA,TIMI flow classification after the patency of IRA and recanalization arrhythmia are the main risk factors of the occurrence of perioperative ES.