Acute kidney injury (AKI) is a major complication in patients with cardiac surgery and is an independent predictor of mortality. However, the optimal intensity of renal replacement therapy for such patients is still controversial. we randomly assigned the patients with Cardiac surgery-associated acute kidney injury (CSA-AKI) to continuous renal replacement therapy with different treatment dose (35ml / kg / h or 25ml/kg／h),The primary study outcome was death from any cause within 14, 28 and 90 days.