Objective To assess the severity of patients with acute-on-chronic liver failure ( ACLF) using Child-Turcotte-Pugh ( CTP) , Model for End-Stage Liver Disease ( MELD) , integrated MELD ( iMELD) , Chronic Liver Failure-Sequential Organ Failure Assessment ( CLIF-SOFA) , and Chronic Liver Failure-Consortium ACLF ( CLIF-C-ACLF) scores, and to investigate the value of these scoring systems in predicting 28-and 90-day mortality rates. Methods A total of 107 patients with ACLF who were hospitalized in Department of Gastroenterology in Xijing hospital from January 2013 to December 2017 were enrolled, and related laboratory markers on days1, 3-5, and 7-9 after diagnosis were collected. The CTP, MELD, iMELD, CLIF-SOFA, and CLIF-C-ACLF scores were calculated, and the receiver operator characteristic ( ROC) curve was used to compare the clinical value of these scoring systems. The t-test or the Satterthwaite t-test was used for comparison of normally distributed continuous data between groups, the Mann-Whitney U test was used for comparison of non-normally distributed continuous data between two groups. The chi-square test was used for comparison of categorical data between groups. Results Among the 107 patients, 44 ( 41. 1%) died within 28 days and 55 ( 51. 4%) died within 90 days. The scores of iMELD, CLIF-SOFA, and MELD at the time of diagnosis had an area under the ROC curve ( AUC) of 0. 81, 0. 73, and 0. 75, respectively, in predicting 28-day mortality, as well as an AUC of 0. 73, 0. 68, and 0. 70, respectively, in predicting 90-day mortality.On days 3-5 and 7-9 after diagnosis, there was no significant difference in the AUC for predicting 28-day mortality between MELD/CLIF-SOFA and iMELD ( Z = 0, 0. 15, 3. 08, and 3. 11, all P > 0. 05) , suggesting that the three scores had a similar predictive ability; on days 7-9 after diagnosis, there was no significant difference in the AUC for predicting 90-day mortality between MELD/CLIF-SOFA and iMELD ( Z = 2. 14 and 1. 98, both P > 0. 05) , suggesting that the three scores had a similar predictive ability. At the time of diagnosis and on days 3-5 and 7-9 after diagnosis, iMELD, CLIF-SOFA, and MELD scores had a significantly higher AUC than CLIF-C-ACLF and CTP scores. Conclusion The iMELD scoring system is proved to be an effective predictive system for short-term mortality in patients with ACLF, and dynamic evaluation of iMELD and CLIF-SOFA scores can effectively predict the prognosis of ACLF patients.