Betaine have protective effects on liver,cardiovascular system,and cancer,but there is no report about I/R injury in heart. So the purpose of this experiment is to study the effect of betaine on I/R injury by Langendorff model and to discuss the mechanisms. SD rat were randomly divided into 4groups: control group(perfused with KH buffer),10~(-4)mol·L~(-1),5×10~(-4)mol·L~(-1),and 10~(-3)mol·L~(-1)(perfused with betaine in different concentration respectively for 10 min before ischemia followed by KH buffer perfused). During the experiment we detected LVEDP,LVDP,dp/dt,and store the tissue to do western blot and TTC staining. The result showed that in control group the recovery rate is 19.6%,after pretreatment of betaine the recovery rate all increased significantly and in a dose-dependent manner. The LVEDP is markedly decreased in betaine treatment groups compare to control group. Coronary flow only in highest betaine treatment group(10~(-3)mol·L~-) is markedly increased compare to control group,other two groups have no change. Western blotting showed that SOD level is significantly increased in betaine treatment group compare to control group and in a dose dependent manner. TTC staining suggested that infarction size is reduced in betaine treatment group compare to control group. Above all,the results suggest that betaine have protect effect on I/R injury in heart and this effect may relate to ROS signaling pathway. Betaine have protective effects on liver, cardiovascular system, and cancer, but there is no report about I / R injury in heart. So the purpose of this experiment is to study the effect of betaine on I / R injury by Langendorff model and to discuss the SD rats were randomly divided into 4 groups: control group (perfused with KH buffer), 10 -4 mol·L -1, 5 × 10 -4 mol·L -1 ), and 10 ~ (-3) mol·L -1 (perfused with betaine in different concentrations respectively for 10 min before Khu buffer perfused). During the experiment we detected LVEDP, LVDP, dp / dt, and store the tissue to do western blot and TTC staining. The result showed that in control group the recovery rate is 19.6% after after pretreatment of betaine the recovery rate all increased significantly and in a dose- dependent manner. The LVEDP is markedly decreased in betaine treatment groups compare to control group. Coronary flow only in highest betaine treatment group (10 ~ (-3) mol·L ~ -) is markedly increased compare to control group, other two groups have no change. Western blotting showed that SOD level is significantly increased in betaine treatment group compare to control group and in a dose dependent manner. TTC staining suggested that infarction size is reduced in betaine treatment group compare to control group Above all, the results suggest that betaine have protect effect on I / R injury in heart and this effect may relate to ROS signaling pathway.