Acute kidney injury (AKI) is a common complication of prolonged cardiopulmonary bypass (CPB) performed during cardiac surgery. There are several known risk factors associated with AKI perioperatively. However, there is little knowledge about CPB and its complications in children with congenital heart disease (CHD) undergoing cardiac surgery. This study aims to identify and analyze the risk factors associated with perioperative AKI due to CPB performed in patients with CHD.The study includes 217 patients with CHD who underwent surgery and CPD at Mie University Hospital. The participants had a bodyweight of 20kg or less;they were classified into two groups:the non-AKI group consisting of 150 cases, and the AKI group containing 67 cases. The risk factors were identified and analyzed.The body surface area (BSA) of each patient (OR 0.461, 95%C.I. 0.317-0.732;p=0.008) , time duration of CPB (OR 1.546, , the maximum level of PF-Hb (OR 2.142, 95%C.I. 1.276-3.998;p=0.011) , and the minimum DO2 value (OR 0.659, 95%C.I. 0.518-0.802;p=0.032) were detected as independent risk factors for the perioperative AKI.