Aim To investigate the hepatotoxic effect of aqueous extract of fructus psoraleae (WEFP) on lipopolysaccharide (LPS)-induced hepatotoxicity in SD rats under immune stress and its mechanism. Methods SD rats were divided into control (CON), LPS, WEFP, LPS+WEFP group. The LPS and LPS+WEFP groups were injected with 4 mg·kg-1 LPS via tail vein; 2 h later, the rats in WEFP group and LPS+WEFP group received the WEFP (1.1 g·kg-1·d-1) by oral gavage for seven consecutive days. Different endpoints such as body weight, liver index, bile flow rate, serum biochemical, histopathological changes, inflammatory cytokines, protein and mRNA expression levels were determined to clarify the liver toxicity and mechanism of WEFP. Results Compared with the CON group, rats in the LPS group had no significant changes in body weight, liver coefficient, serum ALT, AST, and ALP liver injury indicators; mild steatosis in the liver of the rats in the WEFP group did not cause liver damage; for rats in the LPS+WEFP group, body weight and bile excretion decreased, liver coefficient, serum ALT, AST, ALP, TBA levels significantly increased, and IL-1 and TNF-α secretion in the liver increased; at the same time, the pathological changes such as inflammatory reaction, cholestasis, and steatosis appeared in liver, RhoA mRNA and protein expression increased, and TLR4 and ICAM-1 pro-inflammatory gene expression increased, leading to acute liver injury. Conclusions The non-hepatotoxic dose of LPS can cause the same dose of psoralen to show more obvious liver toxicity, leading to the body's immunospecific response. Psoralen can cause immune stress rats to activate the expression of RhoA and other pro-inflammatory genes, further aggravate the release of inflammatory factors,and promote inflammatory reaction damage to liver cells and intrahepatic bile duct tissues,leading to obstruction of bile acid efflux and causing special effects such as heterogeneous liver injury.