Objective To study the effect and intrinsic mechanism of acute suppurative peritonitis associated ascitic fluid (ASPAAF) on experimental liver injury of rats. Methods Thirty-two male or female Sprague-Dawley (SD) rats were randomly divided into two groups: ASPAAF group (n=16) and control group (n=16), in which 8 ml ASPAAF or normal saline (NS) were injected into the peritoneal cavity, respectively. The rats were killed at each time intervals after peritoneal cavity injection (6 h and 12 h) respectively in two groups and specimens were made to detect the levels of serum TNF-α, endotoxin and liver function (AST, ALT and STB). The level of TNF-α in liver tissues was measured. The pathological change of liver was observed by microscope. Results The levels of TNF-α, endotoxin, ALT, AST and STB in serum and the levels of TNF-α in liver tissues at different time points were markedly higher in ASPAAF group compared with those in control group (P＜0.05), and these indexes increased with increasing time in ASPAAF group (P＜0.05). In ASPAAF group, hepatic tissue appeared hydrops, even spotty necrosis and the changes at 6 h and 12 h were not obvious different. No abnormal pathological change of hepatic tissue was found in control group. Conclusion ASPAAF can induce the injury of the liver in rats, which may involved in TNF-α and endotoxin.