Objective:To investigate the risk factors for sepsis in patients severe trauma.Methods:A retrospective case-control study was conducted to analyze the clinical data of 149 patients with severe trauma admitted to General Hospital of Ningxia Medical University from January 2021 to June 2022, including 112 males and 37 females, aged 18-93 years [(50.6±16.3)years]. According to whether the patients developed sepsis, they were divided into sepsis group ( n=66) and non-sepsis group ( n=83). A comparison was made between the two groups in gender, age, measurements of body temperature, heart rate, respiration, systolic blood pressure, diastolic blood pressure, mean artery pressure (MAP), oxygen saturation (SPO 2), white blood cell (WBC), absolute neutrophil count (ANC), percentage of neutrophils (NEUT%), red blood cell count (RBC), hemoglobin (HGB), platelet count (PLT), prothrombin time (PT), activated partial thromboplastin time (APTT), D-dimer level, level of lactic acid, level of blood glucose, quick sequential organ failure assessment (qSOFA), sequential organ failure assessment (SOFA), acute physiology and chronic health evaluation II (APACHE II) score, Glasgow coma scale (GCS), and injury severity score (ISS) within 24 hours of admission, causes of injury, injury sites, number of injury sites, hemorrhagic shock (HS), open injury, endotracheal intubation, length of ICU stay and total length of hospital stay. Univariate analysis and multivariate Logistic regression analysis were used to determine the independent risk factors for severe post-traumatic sepsis. Results:The results of univariate analysis showed that there were statistically significant differences in age, respiration, SPO 2, WBC and ANC, D-dimer level, blood glucose level, qSOFA, SOFA, APACHE II score, GCS, ISS, head and neck injury, open injury, tracheal intubation, length of ICU stay, and total length of hospital stay between the sepsis group and non-sepsis group ( P<0.05 or 0.01); whereas there were no significant differences in gender, underlying disease, body temperature, heart rate, systolic blood pressure, diastolic blood pressure, MAP, NEUT%, RBC, HGB, PLT, PT, APTT, lactic acid level, cause of injury, facial injury, chest injury, abdominal and pelvic injury, limb and pelvic injury, number of injury sites, and HS between the two groups ( P>0.05). Multivariate Logistic regression analysis showed that D-dimer level ( OR=0.97, 95% CI 0.96, 0.99, P<0.01) and tracheal intubation ( OR=15.80, 95% CI 2.14, 116.69, P<0.01) were significantly correlated with sepsis in patients with severe trauma. Conclusion:D-dimer level collected within 24 hours of admission and tracheal intubation are independent risk factors for sepsis in patients with severe trauma.