The changes of proton-translocation across the inner mitochondrial membrane of hepatocytes in endotoxic shock rats were studied.It was showed that: Five hours after shock, the maximum value of fluorescent quenching（ΔA_max）of ACMA(9-anmino-6-chloro-2-meto-acridine) induced by ATP,NADH and succinate was significantly decreased (P＜0.05). The time of maximum fluorescent quenching（T_ΔAmax）and the time of half maximum fluorescent quenching（T_1/2ΔAmax）were significantly prolonged (P＜0.01). It was suggested that the ability of proton translocation across the IMM in endotoxic shock rats was decreased. The membrane fluidity were significantly decreased at the deep level and hydrocarbon chain. The mitochondrial membrane-associated PLA₂ activity, plasma MDA,and mitochondrial MDA contents were significantly increased in endotoxic shock rats. The results showed that PLA₂, and lipid peroxide may be the causes of the changes of proton translocation in endotoxic shock rats.