〔Abstract〕 Objective To explore the protective effect and its mechanism of Jiawei Danshen decoction on hypoxia/ reoxygenation (H/R) injured H9C2 cardiomyocytes from Nrf2–ARE signaling pathway. Methods Drug-containing serum and blank serum of SD rats were prepared, and different concentrations of drug-containing serum of Jiawei Danshen decoction were used to interfere with normal and H/R injury of H9C2 myocardial cells. The experimental dose of Jiawei Danshen decoction was screened by CCK-8 method. H9C2 cardiomyocytes were cultured in vitro to establish H/R injury model. H9C2 cardiomyocytes were randomly divided into six groups: normal group, H/R group, blank serum group (BS group), Jiawei Danshen decoction containing serum group (JDD group), JDD + Nrf2 inhibitor group (JDD + ML385 group) and reactive oxygen species (ROS) scavenger group (NAC group). The morphological changes of cardiomyocytes in each group were compared. Results The serum containing 15% concentration of Jiawei Danshen decoction was selected as the working concentration serum. Compared with the normal group, the degree of cell degeneration and necrosis in H/R group increased under the inverted microscope. The cell morphology of JDD + ML385 group, BS group and H/R group were similar, while the pathological state of H9C2 cardiomyocytes was significantly improved after intervention in JDD group and NAC group. Conclusion The protective effect of Jiawei Danshen decoction against myocardial ischemia_x005freperfusion injury (MIRI) may be realized by activating NrF2-ARE pathway to reduce oxidative stress injury mediated by ROS.