Acetaminophen (APAP) is widely used as an antipyretic agent which is safe at therapeutic doses. However, overdose of APAP induces fatal and non-fatal hepatic necroses. The chemical reactive metabolites of APAP initiate toxicity and inflammatory response within the liver and lead to acute liver failure. However, the mechanism underlying APAP-induced liver injury is unknown. Thioredoxin-1 (TRX-1) is an important redox regulator, which plays roles in resisting oxidative stress, regulating inflammation and inhibiting apoptosis. Panaxatriol saponin (PTS) is one of the biologically active fractions of Panax notoginseng which is a traditional Chinese medicine. The aim of this study was to investigate the mechanism on PTS protecting liver from APAP hepatotoxicity. Mice were divided into three groups, control group, APAP group and APAP combined with PTS group. Alanine aminotransferase (ALT) and tumour necrosis factor-alpha (TNF-α) were detected by ELISA. TRX-1 and pro-caspase-12 were examined by Western blotting. Our results showed PTS inhibited the levels of ALT and TNF-α by APAP. Pretreatment with PTS ameliorated liver injury induced by APAP. The decrease in TRX-1 expression was restored by PTS, as well as decreased pro-caspase-12 expression was inhibited by PTS. These data suggest that PTS has roles in suppressing the hepatotoxicity by APAP. Panaxatriol saponin ameliorated liver injury by APAP through restoring the expression TRX-1 and inhibiting pro-caspase-12 decrease.