Abstract: OBJECTIVE To explore the etiological characteristics, laboratory test indexes and prognosis of the hepatic failure patients with secondary infection. METHODS A total of 120 hepatic failure patients with secondary infection who were treated in Nantong Third People's Hospital from Dec 2019 to Dec 2022 were assigned as the infection group, and 132 hepatic failure patients who did not have secondary infection were assigned as the no infection group. The infection sites and etiological characteristics were analyzed, and the laboratory test indexes and prognosis were observed and compared between the two groups of patients. RESULTS There were significant differences in age and grade of liver function between the two groups (P＜0.05). Among the 120 hepatic failure patients with secondary infection, 60.00% had biliary tract infection, 21.67% had pulmonary infection, and 9.17% had thoracic cavity infection. Totally 195 strains of pathogens were isolated, 111 (56.92%) of which were gram-negative bacteria, 55 (28.21%) were gram-positive bacteria, and 29 (14.87%) were fungi. The levels of serum total bilirubin(TBil), creatinine(Scr), interleukin-17(IL-17), high mobility group protein B1 (HMGB1), D-dimer(D-D) and procalcitonin (PCT) of the infection group were higher than those of the no infection group (P＜0.05); the activated partial thrombin time (APTT) and prothrombin time (PT) of the infection group were longer than those of the no infection group(P＜0.05). The incidence rates of ascites, hepatic encephalopathy, hyponatremia and gastrointestinal hemorrhage were higher in the infection group than in the no infection group(P＜0.05). The 30-day mortality rate of the infection group was higher than that of the no infection group, the length of hospital stay of the infection group was longer than that of the no infection group, and the hospitalization cost of the infection group was more than that of the no infection group (P＜0.05). CONCLUSION The gram-negative bacteria are dominant among the pathogens isolated from the hepatic failure patients with secondary infection. The biliary tract, lung and thoracic cavity are the major infection sites. The laboratory test indexes may facilitate the clinical diagnosis of infection, and the prognosis of the patients with infection may remarkably deteriorate.