Abstract: Objective: To explore the effect and molecular mechanism of epigallocatechin gallate (EGCG) pre-treatment of exosomes secreted by cardiomyocytes on myocardial ischemia/reperfusion (I/R) injury by inhibiting autophagy through miR-30a/Beclin-1 axis.Methods: H9c2 cardiomyocytes were cultured in vitro and pretreated with or without EGCG to establish hypoxia/reoxygenation model.Exosomes were extracted and purified, and an-tagomiR-30a and Beclin-1^+/-mice were constructed using in vivo gene interference or gene knockdown techniques to establish I/R models.Exosomes were injected into myocardium at 30 min after ischemia and the effect of EGCG pretreatment of cardiomyocyte-secreted exosomes(EGCG-exosomes) on I/R was studied.The interaction between miR-30a and Beclin-1 was detected by double luciferase reporter assay.TTC staining was used to detect the area of myocardial infarction.Hematoxylin-eosin(HE) staining was used to observe the morphological chang-es of myocardial cells.The content of cardiac troponin I(cTnI) in serum was detected by enzyme-linked immuno-sorbent assay(ELISA).The number of autophagosomes was observed by transmission electron microscopy.Real-time fluorescence quantitative polymerase chain reac-tion (RT-qPCR) and western blotting were used to de-tect the expressions of miR-30a and autophagy related genes and proteins.Results: Compared with the I/R group, the number of autophagosomes decreased in the exosomes group, and myocardial injury was attenuated; compared with the exosomes group, myocardial in-farct size was reduced, cTnI content and autophagosomes decreased, the expressions of Beclin-1 and LC3-II gene and protein and the expression of cathepsin D protein were down-regulated, and the expression of p62 gene and protein was up-regulated in the EGCG-exosomes group; silencing miR-30a promoted autophagy of myocardial I/R, while administration of EGCG-exosomes reversed the above effect; in addition, knockdown of Beclin-1 and EGCG-exosomes had a synergistic inhibitory effect on autophagy (all P< 0.05).Conclusion: EGCG-exosomes inhibit autophagy through miR-30a/Beclin-1 axis and attenuated myocardial ischemia/reperfusion injury.