Aim To investigate the protection effect of microRNA-22 on ischemic cardiomyocyte. MethodsCardiomyocytes were transfected with microRNA-22 and cell activities were assessed. MTT was used to assess cell activities, EdU to assess DNA proliferation and Caspase-3 to assess cell apoptosis. Results MicroRNA-22 was transducted successfully using adeno-virus. The transduction efficiency reached 95%. Over-expression of microRNA-22 down-regulated PTEN level. Over-expression of microRNA-22 increased cell activities, DNA proliferation and decreased cell apoptosis. Conclusion Over-expression of microRNA-22 protected cardiomyocytes from ischemic injury.