Aim To investigate the long-term clinical efficacy of prophylactic intra-aortic balloon pump(pIABP) insertion before primary percutaneous coronary intervention in the patients with ST-segment elevation myocardial infarction.Methods 646 patients with ST-segment elevation myocardial infarction but without cardiogenic shock, who have received primary percutaneous coronary intervention were enrolled. pIABP group consists of the 25 patients who have received prophylactic intra-aortic balloon pump insertion before percutaneous coronary intervention, while the control group consists of 75 patients selected from the patients without prophylactic intra-aortic balloon pump insertion before percutaneous coronary intervention by propensity score matching method. The clinical features were analyzed and the clinical prognosis of the two groups was compared. Results After propensity score matching, there were no significant differences in the baseline data except the Killips classification and diabetes history(P=0.001 and P=0.018). The median follow-up time was 21 months (interquartile range 1～28 months). There were 7 cases (28%) of all-cause death in the pIABP group and 18 cases (24%) in the control group. There were 6 cases (24%) of cardiogenic death in the pIABP group and 9 cases (12%) in the control group. The incidence of major adverse cardiovascular and cerebrovascular events was 45.3% in the control group and 56% in the pIABP group. By Kaplan-Meier analysis, there were no significant differences in all-cause mortality and cardiogenic mortality between the two groups (P=0.519 and P=0.103 respectively). There was also no significant difference in the cumulative incidence of major adverse cardiovascular and cerebrovascular events between the two groups (P=0.275). The multivariate Cox regress analysis suggested that prophylactic intra-aortic balloon pump insertion did not influence the long-term prognosis after adjustment of Killips classification and diabetes history (P=0.917).Conclusion Prophylactic intra-aortic balloon pump insertion before primary percutaneous coronary intervention does not significantly improve long-term outcomes in hemodynamic stable patients with ST-segment elevation myocardial infarction.