Objective  To explore the protective effect of ginsenoside Rb1 on the myocardial ischemia/reperfusion(I/R) injury in rats in vitro.   Methods  Totally 60 adult male SD rats were randomly divided into 6 groups：sham group，I/R group，ginsenosde Rb1 pretreatment groups(at the doses of 1 μmol/L，5 μmol/L，10 μmol/L and 20 μmol/L，respectively), 10 in each group. The Langendorff perfusion system was used to establish I/R model. The Lab Chart electrophysiological system was used to monitor real-time heart function by monitoring heart rate (HR)，left ventricular development pressure (LVDP) and left ventricular development pressure (±dp/dtmax). TTC staining method  was used to measure myocardial infarct size. The Western blotting were used to assay Beclin 1，LC3，p62 and Lamp 2 expression，respectively. The immunohistochemistry were used to assay Beclin 1 expression.   Results  Ginsenoside Rbl of all the four different concent rations improved the decrease of LVDP and±dp/dtmax arising from myocardial I/R injury. Meanwhile，ginsenoside Rbl significantly decreased the area of cardial infarction.Ginsenoside Rb1 (10 μmol/L) precondition group protected the heart most significantly (P<0.05). The expression of Beclin 1 with I/R increased significantly in the cytoplasm of cardiomyocytes. Moreover, Beclin 1 expression decreased after addition pretreatment with ginsenoside Rb1 (10 μmol/L) (P<0.05). Compared with sham group, we found that the autophagic flux was impaired in I/R group which the expression of Beclin 1，LC3 and p62 increased significantly, as well as the expression of Lamp 2 decreased significantly. On the other hand, pretreatment with ginsenoside Rb1 (10 μmol/L) could reverse impaired autophagic flux (P<0.05).   Conclusion  Ginsenoside Rbl demonstrates pharmacological preconditioning effect and protects against myocardial I/R injury by improving damaged-autophagy flux， the dose of 10 μmol/L precondition protectes the heart most significantly.