Objective To analyze the condition assessment value of cystatin C (CysC) for children with acute kidney injury .Methods 93 cases admitted to acute kidney injury (AKI) in our department from January 2012 to January 2014 ,according to the AKI stag‐ing ,they were divided into AKI1 group ,AKI2 group and AKI3 group .Meanwhile 33 cases of healthy children for concomitant medi‐cal were chosen as a control group .The serum creatinine (SCr) ,blood urea nitrogen (BUN) ,Cys C ,glomerular filtration rate (GFR) and acute physiology and chronic health evaluation Ⅱ (APACHEⅡ rates) were compared in four groups .Analysis of serum Cys C in patients with AKI SCr ,BUN ,GFR and APACHEⅡ score correlation .Compare AKI children SCr ,GFR ,APACHEⅡ and mortality compare different cystatin C levels .Results The SCr ,BUN ,CysC ,GFR and APACHEⅡ scores were significantly differ‐ent in the control group ,AKI1 group ,AKI2 group and AKI3 group ,SCr ,BUN ,CysC ,GFR and aggravation APACHEⅡ score with AKI gradually rise(P<0 .01) .In AKI1 group ,AKI2 group and serum Cys C AKI3 group ,SCr ,BUN and APACHEⅡ scores were positively(P<0 .05) ,but correlated with GFR were negative correlation(P<0 .05) .CysC levels <1 .50 ,1 .50 -2 .00 and>2 .00 SCr ,APACHEⅡ and mortality gradually increased ,with statistically significant difference(P<0 .01);GFR decreased ,with a sig‐nificant difference(P<0 .01) .Conclusion AKI children with elevated serum Cys C prompt with impaired renal function ,serum Cys C and at the same time there is a positive correlation APACHEⅡ score ,which could be used as indicators to assess the severity of illness of children AKI .