Abstract: OBJECTIVE To explore the effects of Sofren on mitochondrial dysfunction and dynamic unbalance induced by H/R injury. METHODS Primary neonatal rat cardiomyocytes were cultured and randomly assigned to five groups based on the sofren that was used and the treatment simulating reperfusion injury: control group， H/R group， sofren preconditioning+H/R group (S+H/R)， H/R+sofren postconditioning group (H/R+S)， sofren pre- and postconditioning +H/R group (S+H/R+S). The intracellular adenosine triphosphate (ATP) level， reactive oxygen species (ROS) accumulation was measured by multifunctional microplate reader，mitochondrial membrane potential (MMP) was measured though JC-1， mitochondrial optic atrophy(OPA1)， dynamin-related protein 1(Drp1) and phosphorylation dynamin-related 1 (p-Drp1) was measured through Western blot in each group. RESULTS The ROS accumulation was inhibited， MMP and higher ATP level was maintained， higher OPA1 and lower p-DRP1 was expressed，preconditioning or postconditioning or pre- and postconditioning by sofren (P<0.05); there is statistical difference of ATP， ROS and MMP values and p-DRP1 expression between S+H/R+S group and S+H/R group，as well as S+H/R+S group and H/R+S， while no statistical difference of OPA1 expression; there is no statistical difference of DRP1 expression between all the five groups. CONCLUSION These results showed that sofren exerted a protective effect on cardiomyocytes injuried by H/R， and the machanism may correlate with rescuing H/R-induced myocardial mitochondrial dysfunction and dynamic unbalance， and further studies are required.