Objective To investigate the effects of fibrin-derived peptide Bβ15-42(FgBβ15-42)on mitophagy in acute kidney injury(AKI)with ischemia-reperfusion at the cellular level.Methods Human kidney-2(HK2)cells were cultured in vitro and ran-domly divided into five groups:normal control group(Control group),hypoxia/reoxygenation(H/R)model group(H/R group),H/R+9μmol/L FgBβ15-42 peptide group(Fg group),H/R+20μmol/L chloroquine group(CQ group),and H/R+9μmol/L FgBβ15-42 peptide+20μmol/L chloroquine group(Fg+CQ group).Control group:cells were homogenized and replaced with complete medium and incubated in an aerobic incubator(5％CO2,21％O2)for 28hours.H/R group:cells were added to sugar-free and serum-free DMEM/F12medium and then placed in a hypoxic incubator(5％CO2,1％O2 and 94％N2)for 24hours,washed with PBS and added to DMEM/F12medium containing serum and then placed in a reoxygenated environment(5％CO2,21％O2)for 4hours.Fg group:mod-eled according to the above method,intervention was performed by adding FgBβ15-42 peptide 9μmol/L to the complete medium when reoxygenation was performed after the completion of hypoxia.CQ group:pre-treatment with chloroquine(20μmol/L)in serum-free medium at the time of homogenization,with the same post-procedural steps as in the H/R group.Fg+CQ group:the intervention was performed according to the dosing sequence of the CQ group and FgBβ15-42 group at different time periods as mentioned above,and the modeling time of the H/R group.After the intervention,CCK-8 was used to detect the cell viability of HK2.The mitochondrial morphol-ogy,mitophagosome structure and number were observed by electron microscope.The expression levels of autophagy related proteins p62 and LC3 were detected by Western blot.Results Compared with the control group,the survival rate of H/R group was decreased(P＜0.01);the mitochondrial damage was obvious,such as swelling and spinous rupture,and the number of mitophagosomes increased.The expression of autophagy protein LC-3 Ⅱ/Ⅰ was up-regulated(P＜0.05),and the expression of autophagy substrate protein p62 was down-regulated(P＜0.01).Compared with H/R group,the survival rate of Fg,CQ and Fg+CQ groups increased(P＜0.01),mito-phagosome was decreased.the expression of LC-3 Ⅱ/Ⅰ was down-regulated(P＜0.01),the expression of p62 was up-regulated(P＜0.05),and autophagy was inhibited.Conclusion The intervention of FgBβ15-42 peptide can reduce the level of autophagy and mitophagy in H/R-AKI cells,and has a protective effect on H/R injury in HK2 cells.