Extracorporeal life support (ECLS) is a world-famous life-saving method. Until now, changes in arterial wave properties due to ECLS have remained unexamined. In this study, we determined the effects of ECLS on arterial wave properties and ventricular/arterial coupling in male Wistar rats with the measured aortic pressure alone. Ascending aortic pressure signals were measured before ECLS and at 30, 60, and 90 min after weaned off. The aortic pressure signal then calculated by fourth-order derivative to obtain an assumed triangular flow wave. The ratio of mean systolic pressure to mean diastolic pressure (Pms/Pmd), a parameter for evaluating the matching condition between myocardial oxygen demand and supply, was significantly higher after ECLS. The magnitude of forward pressure (|Pf|) augmented by ECLS prevailed over the backward pressure (|Pb|), leading to a decline in wave reflection factor. Pms/Pmd was positively linearly correlated with |Pf| (Pms/Pmd = 0.9177 + 0.0078 × |Pf|, r = 0.8677; P < 0.0001). These findings suggest that |Pf| was a predominant factor responsible for the mismatch between the myocardial oxygen demand and supply in rats after ECLS phase of experiment.