Abstract: To investigate the protective effect and mechanism of asiatic acid on mitochondrial cadmium injury in rat liver cells,Cd²⁺induced hepatic mitochondrial permeability transition(MPT)was established,and the mitochondria were randomly divided into five groups of control,25,50,100 mol/L AA and RR(Ruthenium Red)group. Mitochondrial swelling was assessed by measuring the absorbance of their suspension,mitochondrial membrane potential was evaluated according to the uptake of the fluorescent dye rhodamine 123(Rh123),the intramitochondrial Ca²⁺ level was assayed by Ca²⁺ indicator dye fura-2/AM,and transfer of cytochrome c(Cyt c)and apoptosis-inducing factor(AIF)from the intermembrane space to the cytoplasm was determined by Western blot analysis. The results showed that obvious mitochondrial swelling,loss of mitochondrial membrane potential,and release of matrix Ca²⁺ occurred after the addition of 10 μmol/L Cd²⁺. In addition,Cyt c and AIF releasing were detected in the mitochondrial supernatant. However,preincubation with 20,50,100 μmol/L AA could significantly block the above changes. Inhibition rates of 100 μmol/L AA on mitochondrial swelling,mitochondrial membrane potential dissipating,and mitochondrial Ca²⁺,Cyt c and AIF releasing were 49.5%,41.9%,47.9%,62.2% and 66.3%,respectively. The results suggested that AA had significant protection from Cd²⁺-induced rat hepatic mitochondria damage and the mechanisms might relate to its direct inhibitory effect on hepatic MPT.