Objective To study the protective effect and the mechanism of anti-myocardial-ischemia-reperfusion injury of Shen-fu injection through ligating the left anterior descending(LAD) of rats in vivo.Methods The 46 rats were divided into 5 groups randomLy:(1) no-operation group;(2) the control group 1: 30-minute ischemia;(3) pretreatment group 1 with Shen-fu: 30-minute ischemia;(4) the control group 2: 30-minute ischemia followed by 10-minute reperfusion;(5) pretreatment group 2 with Shen-fu: 30-minute ischemia followed by 10-minute reperfusion.The content of malondialdehyde(MDA) and the expression of antioxidant genes of superoxide dismutase 1(SOD1) gene and glutathione S-transferase gene were measured,the ultrastructure of the myocardial cells by transmission electron microscope was observed.The mitochondrial stereology analysis was done.(Results The) MDA of the pretreatment groups with Shen-fu was powful decreased compare with the control groups.The significant decreasing the lesion of the myocardial cell and mitochondrial in ultrastructure were found in the pretreatment groups with Shen-fu.The stereology analysis display that the mitochondrial in the control groups have significant changed compare with the no-operation group.And the mitochondrial in the pretreatment group with Shen-fu was a little different from the no-operation group.Shen-fu up-regulated the expression of SOD1 gene and glutathione S-transferase gene.Conclusion The Shen-fu protect the myocardial cell by reducing the lipid peroxidation.Their protective effects may be partly related to up-regulating the antioxidant gene that increase the ability of antioxidant.