Objective：To retrospectively analyzethe incidence，risk factors，and prognosis of ventricular fibrillation/ventricular tachycardia（VF/VT）within 72 hours of extracorporeal cardiopulmonary resuscitation（ECPR）in patients supported by extracorporeal membrane oxygenation（ECMO）. Methods：ECPR patients admitted to the Emergency Center of the First Affiliated Hospital of Nanjing Medical University from January 2017 to March 2023 were included. Patientswere divided into VF/VT group and nVF/VT group according to the occurrence of VF/VT within 72 hours of ECMO support. risk factors for VF/VT during ECMO support were analyzed through regression analysis，and the impact of VF/VT on clinical prognosis was explored. Results：A total of 95 patients with a mean age of（50.02±15.93）years were enrolled，with males accounting for 66.32%. The 28-day survival rate was 51.58%，and the incidence of VF/VT was 33.33%. Comparison among groups showed that the nVF/VT group had a higher rates of continuous renal replacement therapy，longer ECMO initiation time，and higher lactic acidlevels compared tothe VF/VT group.Troponin T（TnT）levels showed a trend of being higher in the VF/VT group，while the pH value was significantly lower in the VF/VT group compared to the nVF/VT group. Stepwise multivariable logistic regression analysis showed that the risk of maintaining high TNT levels significantly increased after VF/ VToccurrence，with an odds ratio（OR）of 18.156（95%CI：3.620-91.059）. Prolonged ECMO initiation time（OR=1.118，95%CI：1.060- 1.180）and decreased pH value（OR=0.005，95%CI：0.000-0.953）were identified as independent risk factors for VF/VT occurrence. Conclusion：In patients with ECPR，the risk of VF/VT occurring within 72 hours of ECMO support issignificantly increased in patients with severe acidosis or prolonged ECMO initiation time. The onset of VF/VT does not affect the clinical prognosis but may exacerbate myocardial injury.