Objective To learn the clinical characteristics of concurrent acute-on-chronic liver failure( ACLF) and hepatorenal syndrome( HRS),and to investigate the predictive factors for HRS in patients with ACLF. Methods A total of 806 patients with ACLF who were admitted to our hospital from January 2012 to May 2014 were selected and divided into two groups according to the incidence of concurrent HRS. Clinical indices and laboratory test results were analyzed in the two groups,and the multivariate logistic regression analysis was used to figure out independent indices for the prediction of HRS in patients with ACLF. A prediction model was established and the receiver operating characteristic curve was drawn to evaluate the accuracy of the prediction model. Comparison of continuous data between the two groups was made by t test,and comparison of categorical data between the two groups was made by χ2test. Results In all patients with ACLF,229 had HRS and 577 had no HRS. The univariate logistic regression analysis showed that hepatic encephalopathy,peritonitis,infection,age,cystatin C( Cys-C),serum creatinine( SCr),blood urea nitrogen,albumin,prealbumin,total bilirubin,direct bilirubin,total cholesterol,K+,Na+,phosphorus,Ca2 +,prothrombin time,prothrombin activity,international normalized ratio,and hematocrit were significant predictive factors for HRS. The multivariate logistic regression analysis showed that concurrent peritonitis,Cys-C,SCr,and HCO3-were independent predictive factors for HRS in patients with ACLF( OR = 3. 155,P < 0. 01; OR = 30. 773,P < 0. 01; OR = 1. 062,P < 0. 01; OR = 0. 915,P < 0. 05). The model was proved of great value in prediction. Conclusion Concurrent peritonitis,Cys-C,SCr,and HCO3-are effective predictive factors for HRS in patients with ACLF.