Objective To study the predictive value of acute gastrointestinal injury (AGI) grading system introduced into Sequential Organ Failure Assessment (SOFA) score in patients with severe acute pancreatitis (SAP) in order to provide a reliable clinical tool for the evaluation of prognosis of SAP. Methods Patients with acute pancreatitis admitted to ICU from July 2012 to July 2014 were enrolled for study. The criteria of exclusion were the age below 18 years old, pregnancy, or patients without consent to the treatment. A total of 63 patients with 37 males and 26 females aged (47 ±15.3) years were included. The data of their acute physiology and chronic health evaluation (APACHE) Ⅱ score, the highest SOFA score and AGI grade within the first week, and the 28-day mortality rate were collected. Patients without AGI were defined as zero point, and AGI grade I -IV were defined as 1-4 points. The receiver operating characteristic curve (ROC) was used to evaluate the value of APACHEⅡ score, SOFA score, and SOFA + AGI score in predicting the prognosis of SAP. The areas under ROC curve (AUC) of the APACHEⅡ score, SOFA score, and SOFA +AGI score were compared with MedCalc software, and P value less than 0.01 was considered to be statistical significance. Results (1) The 28-day mortality of the 63 patients with SAP was 20.6% (13/63), in which 50 patients in the survival group, 13 patients in the death group. The APACHEⅡ scores of two groups were (15.62 ± 4.33 vs. 12.10 ± 3.74, P =0.0048), the SOFA scores were (14.77 ± 3.09 vs. 9.24 ± 2.88, P <0.01), and the SOFA +AGI scores were (18.77 ± 3.09 vs. 10.74 ± 3.17, P <0.01). (2) The AUC of APACHEⅡ score was 0.748 ± 0.084 (95% CI: 0.622-0.849), the AUC of SOFA score was 0.902 ± 0.059 (95% CI: 0.801-0.962), and the AUC of SOFA +AGI score was 0.963 ± 0.037 (95% CI, 0.882-0.994) ; There was no significant difference in AUC between APACHEⅡ score and SOFA score (P =0.10) , and there was statistical significance between the AUC of APACHEⅡ score and that of SOFA +AGI score (P =0.013) , and the difference in AUC between SOFA score and SOFA +AGI score was statistically significant (P =0.008). The Youden index and the positive likelihood ratio of SOFA +AGI score system were the greatest to be 0.863 and 15.38, respectively. Conclusions SOFA scoring system has better predictive value in patients with SAP when AGI grading system was introduced into it. Key words: Acute gastrointestinal injury grading system; APACHEⅡ score; SOFA score; Severe acute pancreatitis; Prognosis