Objective To investigate the incidence and mortality of acute kidney injury (AKI) in posttraumatic patients, and to analyze the risk factors influencing the incidence and outcomes of AKI. Methods Totally 4 221 patients with trauma who were admitted to No. 309 Hospital of PLA between Jan. 2004 and Jan. 2014 were screened and subjected to a retrospective study, and the incidence rate of AKI and mortality were analyzed. Multivariate logistic regression analysis was conducted to identify the risk factors for the incidence and prognosis of the patients with AKI. Results The incidence of AKI in posttraumatic patients in this study was 11.6% (489/4 221) according to the classification and diagnosis criteria from Kidney Disease:Improving Global Outcomes (KDIGO), and 46.0% (225/489) of them died prior to hospital discharge. There was an increasing hospital mortality tendency with the increase of AKI severity, with the hospital mortality rates being 30.1% (84/279), 54.6% (53/97), and 77.9% (88/113) in AKI patients with KDIGO 1, 2, and 3 stage, respectively. Multivariate logistic regression analysis showed that increase of age, acute physiology and chronic health evaluation Ⅱ (APACHE Ⅱ) scores on admission > 17, injury severity score (ISS) on admission > 16, severe head injury, abdominal organ injury, rhabdomyolysis, shock and respiration system dysfunction were risk factors for occurrence of AKI (P<0.01). Meanwhile, several factors were significantly related to the death of patients with AKI; they included ISS>25, severe head injury, KDIGO stage 3, cardiovascular and respiratory system dysfunction (P < 0.05,P < 0.01). Conclusion AKI is a common clinical complication with high mortality in posttraumatic patients. To prevent severe complications after trauma is the key for improving the prognosis of patients.