Abstract: Objective　To assess the role of urinary neutrophil gelatinase-associated lipocalin (uNGAL) and urinary N-acetyl-beta-D glucosaminidase (NAG) in risk stratification and prognosis for critically ill patients with acute kidney injury (AKI). Methods　A total of 101 critically ill patients with AKI were included in the AKI group, and another 27 critically ill patients without AKI during the same period were included as the control group. Clinical and experimental indicators, including serum creatinine, serum potassium, serum albumin, anion gap, uNGAL, urinary NAG, urinary protein and urinary microalbuminuria were compared between the two groups. Based on the severity of kidney injury, patients were divided into Stage 1 group (n=40), Stage 2 group (n=36) and Stage 3 group (n=25). Besides, regarding the survival status of discharge，patients were divided into survival group  (n=63) and death group (n=38). The indicators we collected were compared with different severity and living state. Logistic analysis was used to find out the independent risk factors affecting the prognosis of critically ill patients with AKI. The receiver operating characteristics (ROC) curve was used to evaluate the predictive ability of uNGAL, urinary NAG and uNGAL combined with urinary NAG in critically ill patients with AKI. Results Compared with control group, the levels of uNGAL, urinary NAG, urinary protein, urinary microalbuminuria and serum creatinine increased and the level of serum albumin decreased in AKI group (P＜0.01). The subgroup analysis indicated that the levels of uNGAL and urinary NAG increased with the severity of kidney injury in critically ill patients (P＜0.05). At the same time, compared with the survival group，the levels of uNGAL，urinary NAG，urinary microalbumin urinary protein and serum creatinine were significantly higher and the level of serum albumin was lower in death group (P＜0.05). Logistic regression analysis showed that the increased levels of uNGAL and urinary NAG were the independent risk factors for prognosis in patients. The ROC curve indicated the area under curve (AUC) of uNGAL combined with urinary NAG was 0.886, which was superior to the uNGAL (0.850) and urinary NAG (0.784) separately. Conclusion uNGAL combined with urinary NAG is helpful for evaluating the severity and prognosis of critically ill patients with AKI.