Objective To explore the influencing factors of recovery of renal function in the elderly septic patients with acute kidney injury (AKI). Methods A retrospective analysis was made of the clinical data of 137 elderly septic AKI patients in Danzhou People′s Hospital from January 2019 to September 2022. According to the recovery of renal function on 90 days after the diagnosis of AKI, they were divided into recovery group (n=62) and non-recovery group (n=75). The two groups were compared in baseline data, biochemical indicators, routine blood indicators, and infection indicators. SPSS statistics 22.0 was used for data analysis. According to the data type, comparisons between the two groups were performed by t-test or Mann-Whitney U test. Logistic regression was used to analyze the independent risk factors of non-recovery of renal function in the elderly septic AKI patients, and receiver operating characteristic (ROC) curve was drawn to evaluate the value of each independent risk factor in predicting non-recovery of renal function in them. Spearman correlation analysis was used to analyze the correlation between blood magnesium level and clinical indicators. Results Multivariate logistic regression analysis showed that old age (OR=1.982,95%CI 1.376-3.150), companied with anemia (OR=4.938,95%CI 4.152-13.290), high urea (OR=1.772,95%CI 1.195-2.716), high serum creatinine (SCr) (OR=2.105,95%CI 1.419-3.702), high red blood cell distribution width (RDW) (OR=5.370,95%CI 4.826-14.353), hypomagnesemia (OR=4.712,95%CI 3.973-12.650), long duration of continuous renal replacement therapy (CRRT) (OR=1.942,95%CI 1.308-3.025), long duration of oliguria or anuria (OR=1.873,95%CI 1.306-2.980), use of nephrotoxic drugs (OR=5.520,95%CI 4.973-16.228), high acute physiology and chronic health evaluation Ⅱ (APACHEⅡ) score (OR=2.183,95%CI 1.552-3.894), high lactic acid (OR=3.115,95%CI 2.317-9.913),high C-reactive protein (CRP) (OR=2.773,95%CI 1.985-6.214) and high procalcitonin (PCT) (OR=4.928,95%CI 4.105-14.106) were independent risk factors of the failed recovery of renal function in the elderly septic AKI patients (P<0.05) . The ROC curve analysis showed that 10 risk factors in combination had the highest area under ROC curve (0.962,95%CI 0.901-0.998) in predicting the failed recovery of renal function with a sensitivity of 98.6% and a specificity of 85.2%. Conclusion The old age, companied with anemia, high urea, high SCr, high RDW, hypomagnesemia, long duration of CRRT, long duration of oliguria or anuria, use of nephrotoxic drug, high APACHEⅡscore, high lactic acid, high CRP and high PCT are the risk factors of the non-recovery of renal function in the elderly septic AKI patients, and the combination of the 10 factors has high predictive value.