Objective:To investigate the value of serum miR-214-5p level in predicting acute kidney injury(AKI)after cardiac surgery in children.Methods:From January 2015 to December 2019, 102 children with congenital heart disease underwent extracorporeal circulation in Haikou Maternal and Child Health Hospital were selected.The children were divided into AKI group( n=28)and non-AKI group( n=74). The levels of serum miR-214-5p, serum creatinine(Scr), cystatin C(Cys-C)and kidney injury molecule-1(KIM-1)were measured three hours after operation in both groups.Multivariate logistic regression was used to analyze the risk factors of AKI after cardiac surgery in children.The values of miR-214-5p, Scr, Cys-C and KIM-1 levels in predicting AKI in children after cardiac surgery were analyzed by receiver operating characteristic(ROC)curve. Results:The levels of serum miR-214-5p[(3.14±1.36)vs.(0.95±0.47)], Scr[(490.35±93.62)μmol/L vs.(108.26±22.40)μmol/L], Cys-C [(3.27±0.85)mg/L vs.(0.86±0.24)mg/L] and KIM-1 [(26.83±8.70)μg/L vs.(6.42±1.18)μg/L] in AKI group were significantly higher than those in non-AKI group(all P<0.05). Multivariate logistic regression analysis showed that serum miR-214-5p, Scr, Cys-C and KIM-1 levels were independent risk factors for AKI in children after cardiac surgery( OR=2.518, P<0.001; OR=1.630, P=0.035; OR=1.974, P<0.001; OR=2.902, P<0.001). ROC curve analysis showed that the area under the curve(0.958, 95% CI: 0.905-0.996)of miR-214-5p, Scr, Cys-C and KIM-1 combined prediction of AKI were the largest, and its sensitivity and specificity were 98.5% and 86.3%, respectively. Conclusion:The level of serum miR-214-5p is significantly higher in children with AKI after cardiac surgery, which is an independent risk factor for AKI after cardiac surgery, and the combination of Scr, Cys-C and KIM-1 levels can better predict the occurrence of AKI.