To observe the clinical characteristics and prognosis of patients with acute respiratory distress syndrome (ARDS) in sepsis combined with acute gastrointestinal injury (AGI) of different grades, and to further explore the risk factors associated with the poor prognosis of patients. The clinical data of patients with septic ARDS admitted to the intensive care unit (ICU) of Tianjin First Central Hospital from March to October 2023 were collected. According to the 2012 European Association of Critical Care Medicine AGI definition and grading criteria, the patients were categorized into AGI grade 0- IV groups. The clinical characteristics and 28-day clinical outcomes of the patients were observed; the risk factors related to the prognosis of patients with septic ARDS combined with AGI were analyzed by using univariate and multivariate Logistic regression; and the receiver operator characteristic curve (ROC curve) and calibration curves were plotted to evaluate the predictive value of each risk factor on the prognosis of patients with septic ARDS combined with AGI. A total of 92 patients with septic ARDS were enrolled, including 7 patients in the AGI 0 group, 20 patients in the AGI I group, 38 patients in the AGI II group, 23 patients in the AGI III group, and 4 patients in the AGI IV group. The incidence of AGI was 92.39%. With the increase of AGI grade, the ARDS grade increased, and acute physiology and chronic health evaluation II (APACHE II), sequential organ failure assessment (SOFA), intra-abdominal pressure (IAP), white blood cell count (WBC), neutrophil count (NEU), lymphocyte count (LYM), lymphocyte percentage (LYM%), and 28-day mortality all showed a significant increasing trend, while the oxygenation index (PaO2/FiO2) showed a significant decreasing trend (all P < 0.05). Pearson correlation analysis showed that APACHE II score, SOFA score, and ARDS classification were positively correlated with patients' AGI grade (Pearson correlation index was 0.386, 0.473, and 0.372, respectively, all P < 0.001), and PaO2/FiO2 was negatively correlated with patients' AGI grade (Pearson correlation index was -0.425, P < 0.001). Among the patients with septic ARDS combined with AGI, there were 68 survivors and 17 deaths at 28 days. The differences in APACHE II score, SOFA score, ARDS grade, AGI grade, PaO2/FiO2, IAP, AGI 7-day worst value, length of ICU stay, and total length of hospital stay between the survival and death groups were statistically significant. Univariate Logistic regression analysis showed that SOFA score [odds ratio (OR) = 1.350, 95% confidence interval (95%CI) was 1.071-1.702, P = 0.011], PaO2/FiO2 (OR = 0.964, 95%CI was 0.933-0.996, P = 0.027) and AGI 7-day worst value (OR = 2.103, 95%CI was 1.194-3.702, P = 0.010) were the risk factors for 28-day mortality in patients with septic ARDS combined with AGI. Multivariate Logistic regression analysis showed that SOFA score (OR = 1.384, 95%CI was 1.153-1.661, P < 0.001), PaO2/FiO2 (OR = 0.983, 95%CI was 0.968-0.999, P = 0.035) and AGI 7-day worst value (OR = 1.992, 95%CI was 1.141-3.478, P = 0.015) were the independent risk factors for 28-day mortality in patients with septic ARDS combined with AGI. ROC curve analysis showed that SOFA score, PaO2/FiO2 and AGI 7-day worst value had predictive value for the 28-day prognosis of patients with septic ARDS combined with AGI. The area under the ROC curve (AUC) was 0.824 (95%CI was 0.697-0.950), 0.760 (95%CI was 0.642-0.877) and 0.721 (95%CI was 0.586-0.857), respectively, all P < 0.01; when the best cut-off values of the above metrics were 5.50 points, 163.45 mmHg (1 mmHg≈0.133 kPa), and 2.50 grade, the sensitivities were 94.1%, 94.1%, 31.9%, respectively, and the specificities were 80.9%, 67.6%, 88.2%, respectively. The incidence of AGI in patients with septic ARDS is about 90%, and the higher the AGI grade, the worse the prognosis of the patients. SOFA score, PaO2/FiO2 and AGI 7-day worst value have a certain predictive value for the prognosis of patients with septic ARDS combined with AGI, among which, the larger the SOFA score and AGI 7-day worst value, and the smaller the PaO2/FiO2, the higher the patients' mortality.