Objective To explore the effect of different application timings of continuous renal replacement therapy(CRRT) in patients with sepsis and acute kidney injury.Methods A retrospective analysis was conducted on 84 patients receved CRRT with sepsis and AKI stage 2/3 admitted to the Department of Intensive Care Unit, People′s Hospital of Xinhui District in Jiangmen City, Guangdong Province from April 2018 to August 2019.According to the AKI staging in 2012 KDIGO guidelines, patients with sepsis and AKI stage 2 for CRRT were selected as the early group (41 cases), and patients with sepsis and AKI stage 3 for CRRT were selected as the late group (43 cases).The levels of inflammatory mediators (interleukin-10 [IL-10], interleukin-6 [IL-6], tumor necrosis factor-α [TNF-α]and procalcitonin[PCT]) before and after CRRT for 72h were compared between the two groups.The length of hospital stay, total length of hospital stay, fatality rate at 90 days and fatality rate in hospital were compared between the two groups.Results The PCT, IL-6, IL-10 and TNF-α levels after CRRT for 72h in the early group were lower than those in the late group,and the differences were statistically significant (P<0.05).The length of ICU stay and total length of hospital stay in the early group were shorter than those in the late group, and the differences were statistically significant (P<0.05).The fatality rate at 90 days and fatality rate in hospital in the early group were lower than those in the late group, with statistically significant differences (P<0.05).Conclusion The application effect of different application timings of CRRT in patients with sepsis and acute kidney injury are varies greatly.Compared with sepsis and AKI stage 3 for CRRT, sepsis and AKI stage 2 for CRRT could effectively reduce inflammatory response, shorten the length of ICU stay and total length of hospital stay, and reduce the fatality rate at 90 days and fatality rate.