Objective To analyze risk factors of acute kidney injury （AKI） after cardiac surgery in adults and develop a clinical score system to predict postoperative AKI. Methods Clinical data of 3 500 consecutive patients undergoing cardiac surgery from June 2010 to April 2011 in Beijing Anzhen Hospital of Capital Medical University were retrospectively analyzed. According to whether they had postoperative AKI，all these patients were divided into AKI group and non-AKI group. AKI group was consisted of 1 407 patients （40.2%） with a mean age of 58±12 years，including 1 004 male patients （71.4%）. The non-AKI group was consisted of 2 093 patients （59.8%） with a mean age of 55±13 years，including 1 259 male patients （60.2%）. Predictive score system of postoperative AKI was established by univariate analysis between the AKI and non-AKI group and multivariate logistic regression and then verified. Results The predictive score system was as followed：male gender （2 points），every 5 years older than 60 years （1 point），diabetes mellitus （2 points），preoperative use of angiotensin converting enzyme inhibitor or angiotensin AT1 receptor blocker （1 point），every 10 ml / （min·1.73 m2） of preoperative estimated glomerular filtration rate （eGFR） under 90 ml / （min·1.73m2） （1 point），preoperative NYHA class Ⅳ （3 points），cardiopulmonary bypass time＞120 minutes （2 points），intraoperative hypotension duration＞60 minutes （2 points），postoperative hypotension duration＞60 minutes （3 points），postoperative peak dosage of intravenous furosemide＞100 mg/day （3 points），postoperative peak dosage of intravenous furosemide 60-100 mg/day （2 points），and postoperative mechanical ventilation time＞24 hours （2 points）. The predictive score system presented a good discrimination ability with the area under the receiver operating characteristic（ROC）curve of 0.738 with 95% CI 0.707 to 0.768，while it also presented a good calibration with Hosmer-Lemeshow statistic （P=0.305）. Conclusion A clinical predictive score system for AKI after cardiac surgery in adults is established，which may help clinicians implement early preventive interventions.