Objective To explore the possible mechanism of Jiawei Danshen Yin（ 加味丹参饮） in treating cardiac reperfusion injury. Methods H9C2 cardiac muscle cells in vitro were randomized into 6 groups

with 6 multiple pores in each group. The blank serum group was cultured in culture medium containing 15% of blank serum for 29 h.The hypoxia preconditioning group was cultured in hypoxia medium for 20 min

and then was given oxygen for 20 min

following another hypoxia culture for 20 min. After then the cells were moved into blank serum medium and routinely cultured for 24 h

following cultured in hypoxic medium for 2 h

and then given oxygen for 3 h. The hypoxia/reoxygenation group was cultured in culture medium containing 15% of blank serum for 24 h

then was moved into hypoxia medium and cultured in hypoxia condition for 2 h

then in oxygenation condition for 3 h. The serum containing medicine group was cultured in culture medium containing 15% of medicine serum in normal condition for 24 h

and then was in hypoxia condition for 2 h

following in oxygenation condition for another 3 h. The serum containing medicine + autophagy inhibitor group was preconditioned by 10mmol/L 3-methyladenine for 30 min; the following treatment steps were the same as the serum containing medicine group. The serum containing medicine + autophagy agonist group was preconditioned by 100 nmol/L rapamycin for 30 min; the other treatment steps were the same as the serum containing medicine group. Growth and form changes of cardiac muscle cells in each group were examined with inverted microscope. The leakage rate of lactate dehydrogenase（ LDH） in cell culture supernatant in each group was detected with colorimetric method. The form and number changes of myocardial cell autophagosome were examined with transmission electron microscope. The expressions of autophagy related protein LC3 Ⅱ and Beclin1 in each group were detected with Western blot method. Results Compared with that in the blank serum group

the degree of degeneration and necrosis of myocardial cells increased under microscope

there were a few autophagosome under electron microscope

the leakage rate of LDH in medium increased

and the level of Beclin1 protein increased in the hypoxia/reoxygenation group（ P < 0. 05 or P < 0. 01）. Compared with the hypoxia/reoxygenation group

the degree of degeneration and necrosis of myocardial cells decreased

the number of autophagosome increased under electron microscope

the leakage rate of LDH in medium decreased obviously

and the expressions of LC3 Ⅱ and Beclin1 protein increased in the serum containing medicine group and the serum containing medicine + autophagy agonist group（ P <0. 05）. Conclusion Jiawei Danshen Yin might strengthen autophagy by up-regulate the expressions of autophagy related protein LC3Ⅱ and Beclin1 to protect injured cardiac muscle cells.