Objective The aim of this study was to determine the effect of a new method of cardiac assistant therapy with an extra-aortic balloon pump on the experimental dogs in which myocardial ischemia or infarction were induced, and to ob serve its effectiveness and feasibility. Methods Twelve animal models of myocardia 1 infarction were established with the method of left anterior descending coronary artery ligation. They were divided randomly into two groups, six in the experimental group and six in the untreated group. The end points observed were the differences between the two groups in the blood pressure, cardiac function, myocardial enzymes, infarction size and routine blood variables before procedure, 1,2, 3, 4, 5 and 6 hours after myocardial infarction. Results All six dogs in the experimental group were survived, with a mortality rate of 0.The number of death in the control group was three, with a mortality rate of 50%. Measurements such as mean blood pressure,cardiac output, cardiac index in the experimental group were better than those in the control group ( P ＜ 0.05 ). Mean heart rate before myocardial infarction in the experimental group was 156 beats per minute, as compared with 148 beats per minute in the control group, and was 128 vs. 67 beats per minute respectively six hours after myocardial infarction. The cardiac output was 3.48 vs. 4.98 liters per minute before myocardial infarction and was 6.10 vs. 0.85 liters per minute six hours after myocardial infarction. The average pressure was 94 mm Hg vs. 99 mm Hg before myocardial infarction and was 70 mm Hg vs. 33 mm Hg six hours after myocardial infarction. Conclusion The extra-aortic balloon pump significantly improved the hemodynamic variables of the experimental animals after myocardial infarction and reduced mortality. Injury to the blood cells may be the potential disadvantage.