Objective To observe the effects of Salvianolic acid A (SAA) on heart rate variability (HRV) and myocardial injury in myocardial ischemia reperfusion injured (MI/RI) rats. Methods Sixty SD rats were divided into 6 groups randomly (n=10); the sham group, the MI/RI model group, high, middle and low-dose SAA group (2 mg/kg, 1 mg/kg and 0.5 mg/kg) and positive control group (2 mg/kg Diltiazem). The MI/RI model was made by ligating the left anterior descending branch of coronary artery in rats. Before ligation, the rats were intravenously administered with corresponding drugs. The changes of electrocardiogram of J point and HRV parameters were analyzed. At the end of reperfusion, the myocardial infarct size was measured by using Evans blue and tetrazolium chloride (TTC) double staining. The changes of plasma aspartate aminotransferase (AST), lactate dehydrogenase (LDH), creatine kinase (CK) and its isoenzyme (CK-MB), superoxide dismutase (SOD), malondialdehyde (MDA) and nitric oxide (no) content were also detected. Results Compared with MI/RI model group, SAA low, middle and high dose group and Diltiazem group were significantly reduced the total or average value of J point during reperfusion(P<0.05,P<0.01),reduced myocardial infarct size and inhibited the rising of AST, CK-MB and CK activities(P<0.05,P<0.01), and increased the standard deviation of RR intervals (SDNN), the root-mean-square of successive differences (RMSSD), HRV triangle index (tr. Ind) and high frequency (HFnu), reduced the low frequency (LFnu) and the ratio of LF/HF(P<0.05, P<0.01). Moreover, SAA could significantly increase the content of NO and reduce the content of MDA (P<0.05). Conclusion SAA could increase HRV and reduce myocardial infarction area in MI/RI rats, its mechanism of action maybe related with antioxidant effects.