Abstract: OBJECTIVE To explore the association of systemic immune-inflammation index (SII) and renal resistive index (RRI) with renal hemodynamic characteristics of the sepsis patients complicated with acute kidney injury (AKI) and analyze their values in prediction of prognosis. METHODS A total of 96 sepsis patients complicated with AKI who were treated in Shaoxing People's Hospital from Jun. 2023 to Dec. 2025 were enrolled in the study and were divided into the survival group with 79 cases and the death group with 17 cases according to the 28-day survival status. Pearson correlation analysis was performed for the association of SII and RRI with serum creatinine (Scr), urine acid (UA), pulsatility index(PI) and mean velocity. The efficiencies of SII and RRI in prediction of the prognosis were analyzed by receiver operating characteristic curve (ROC). RESULTS The Acute Physiology and Chronic Health Evaluation (APACHE) II score, proportion of patients who received continuous renal replacement therapy (CRRT), Scr, C-reactive protein (CRP), UA, SII, RRI and PI were higher in the death group than in the survival group (P＜0.05); the end-diastolic flow velocity (Vmin), peak systolic flow velocity (Vmax), and average flow velocity were lower in the death group than in the survival group(P＜0.05). The result of Pearson analysis showed that the SII and RRI were positively correlated with Scr, UA and PI, while they were negatively correlated with the average flow velocity(P＜0.05). ROC curve analysis indicated that SII and RRI had certain values in prediction of death of the patients; the areas under the curves (AUCs) were 0.708 and 0.723, respectively; the sensitivity were 68.43% and 71.56%, respectively; the specificities were 67.25% and 70.17%, respectively. The predictive value of the joint detection of the two indexes was high(AUC=0.764, the sensitivity 74.99%, the specificity 73.64%). CONCLUSIONS The SII and RRI of the sepsis patients complicated with AKI are remarkably associated with the renal hemodynamic indicators and can be used as effective biological indicators for assessment of 28-day prognosis of the sepsis patients complicated with AKI. The joint detection of the two indicators can remarkably raise the efficiency in prediction of the risk of 28-day death.