OBJECTIVE To analyze related risk factors of sepsis complicated acute kidney injury (AKI), and to explore the precaution equation for early clinical diagnosis. METHODS A retrospective review of patients with sepsis complicating AKI admitted to intensive care unit (ICU) of Affiliated Hospital of Binzhou Medical University from April 2011 to April 2013 were enrolled. Fifty-eight sepsis patients without AKI were enrolled as control. Eleven indexes including age, mean arterial pressure (MAP) score, sequential organ failure assessment (SOFA) score, acute physiology and chronic health evaluation II (APACHE II) score, 24-hour urine volume, 24-hour net liquid intake score, serum creatinine (SCr) score, blood urea nitrogen (BUN), oxygenation index, blood lactic acid score and plasma albumin were collected as possible risk factors for AKI in sepsis patients. The risk factors and calculation of the critical value were analyzed by multiple factor logistic regression analysis. RESULTS Nine factors with statistical significance for AKI in sepsis patients analyzed with univariate analysis were substituted in logistic regression model including MAP score, SOFA score, APACHEII score, 24-hour urine volume, 24-hour net liquid intake score, SCr score, BUN, oxygenation index, blood lactic acid score. After variable screening SCr score, MAP score, 24-hour net liquid intake score and blood lactic acid score were substituted in regression equation: Y=0.237X1 + 0.139X2 + 0.057X3 + 0.051X4 (X1, X2, X3, X4 typified SCr score, MAP score, blood lactic acid score and 24-hour net liquid intake score), F=125.897, P=0.000. The diagnostic cutoff appeared as 0.778. The sensitivity, the specificity, the Youden index, positive predictive value and negative predictive value were 80%, 100%, 0.8, 100% and 74%, respectively. CONCLUSIONS SCr score, MAP score, blood lactic acid score and 24-hour net liquid intake score were risk factors of sepsis complicating AKI. When the value higher than 0.778 from regression equation Y=0.237X1 + 0.139X2 + 0.057X3 + 0.051X4, it hinted there was risk related to AKI in sepsis patients. The equation can help the clinicians diagnose sepsis and AKI earlier.