Objective To investigate the changes in coagulation system in acute decompensated cirrhosis （ADC） patients with or without sepsis and the association of these changes with short-term prognosis. Methods A prospective study was conducted among 116 ADC patients who were hospitalized in Nanfang Hospital from January 2021 to July 2023，among whom there were 86 patients with sepsis and 30 patients without sepsis，and 54 patients with sepsis alone who had no chronic liver disease were enrolled as control group. Thromboelastography （TEG） and other conventional coagulation parameters were used to comprehensively evaluate the coagulation function of patients. The data including TEG results and short-term prognosis were collected，and a correlation analysis was performed. The independent-samples t test was used for comparison of normally distributed continuous data between two groups，and 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 two groups. The Spearman correlation coefficient was calculated to investigate the correlation between different variables. The Logistic regression model was used to perform the univariate and multivariate analyses. Results For the ADC patients with sepsis，the lungs and bloodstream were the main infection sites，and bacteria were the main pathogenic microorganism. TEG results showed that compared with the patients with sepsis alone，the patients with ADC and sepsis had a significant reduction in median maximum amplitude （MA），a significant increase in coagulation time （K time），and a significant reduction in α angle （all P<0.05）； the patients with ADC and sepsis had a significantly longer reaction time （R time） than those with ADC alone （P=0.02），and the patients with sepsis alone had a significantly longer R time than those with ADC and sepsis （P=0.04）. There was no correlation between MA and platelet count in the patients with ADC and sepsis （r=-0.133，P=0.057），while there was a significant correlation between MA and platelet count in the patients with sepsis alone （r=0.595，P=0.001）. SOFA score was negatively correlated with MA in sepsis patients with or without ADC （r=-0.503 and -0.561，both P<0.001），and for the patients with ADC and sepsis，R time，K time，and α angle were weakly correlated with SOFA score and had a relatively strong correlation with APTT （all P<0.05）. The patients with ADC alone all survived within 90 days，and compared with the death group，the patients with sepsis alone who survived had significantly higher values of MA and α angle （all P<0.05）； there was a significant difference in α angle on day 90 between the survival group and the death group，no matter whether the patients were comorbid with ADC or not （both P<0.01），while for the patients with ADC and sepsis，there was no significant difference in MA value on day 90 between the survival group and the death group （P>0.05）. Conclusion For ADC patients comorbid with sepsis，coagulation function assessment and monitoring should be taken seriously in clinical practice，and TEG parameters and SOFA score should be monitored when necessary to develop individualized treatment regimens.