Objective To analyze the predictive effect of mononuclear-lymphocyte ratio（MLR）combined with free triiodothyronine（FT₃）on the survival of patients with hepatitis B virus-related acute-on-chronic liver failure（HBV-ACLF）．Methods In the study,187 patients with HBV-ACLF from January 2019 to January 2022 in our hospital were included,and the survival status of the patients was followed up for 90 days．Among them,69 patients were included in the death group and the rest 118 patients were included in the survival group．The data of the two groups of patients were analyzed by univariate analysis,and the statistically significant factors were analyzed by Logistic multifactor analysis．The risk factors of death in patients with HBV-ACLF were analyzed,and the predictive effect of MLR combined with FT₃ on the death of HBV-ACLF was analyzed．Results The age,incidence of cirrhosis,primary peritonitis,hepatorenal syndrome,electrolyte disturbance,ratio of neutrophil to lymphocyte count,international standardized ratio,model for end stage liver disease,MLR,creatinine,white blood cell count and total bilirubin of the patients in the death group were higher than those in survival group,and the levels of serum sodium,FT₃ and total cholesterol were lower than those in survival group,the differences were significant（P<0.05）．The results showed that MLR≥0.60,FT₃≤2.50 pmol/L were risk factors for death of HBV-ACLF patients（P<0.05）．MLR,FT₃,MLR+FT₃ had certain predictive value for the death of HBV-ACLF patients,but the predictive value of MLR+FT₃ was higher than other single prediction．Conclusions MLR≥0.60 and FT₃≤2.50 pmol/L are risk factors for death of patients with HBV-ACLF（P<0.05）,and the combination of the two has a better predictive value for death of patients with HBV-ACLF．