Abstract: Objective To explore the role of mitochondrial permeability transition pore (mPTP) in mediating the protective effect of gastrodin against oxidative stress damage in H9c2 cardiac myocytes. Methods H9c2 cardiac myocytes were treated with H2O2, gastrodin, gastrodin+H2O2, cyclosporin A (CsA), or CsA+gas+H2O2 group. MTT assay was used to detect the survival ratio of H9c2 cells, and flow cytometry with Annexin V-FITC/PI double staining was used to analyze the early apoptosis rate after the treatments. The concentration of ATP and level of reactive oxygen species (ROS) in the cells were detected using commercial kits. The mitochondrial membrane potential of the cells was detected with laser confocal microscopy. The expression of cytochrome C was detected with Western blotting, and the activity of caspase-3 was also assessed in the cells. Results Gastrodin pretreatment could prevent oxidative stress-induced reduction of mitochondrial membrane potential, and this effect was inhibited by the application of CsA. Gastrodin significantly lowered the levels of ROS and apoptosis-related factors in H2O2-exposed cells, and such effects were reversed by CsA. CsA significantly antagonized the protective effect of gastrodin against apoptosis in H2O2-exposed cells. Conclusions Gastrodin prevents oxidative stress-induced injury in H9c2 cells by inhibiting mPTP opening to reduce the cell apoptosis.