Aim To study the efficacy of early using tirofiban on heart function in patients with acute ST-segment elevation myocardial infarction （STEMI） accepted percutaneous coronary intervention （PCI） and its safety. Methods According to tirofiban administration time,60 cases of patients with STEMI were randomly divided into two groups: （1）early group （n＝30）: tirofiban was given before entering the emergency room and PCI （2）control group （n＝30）: tirofiban was given during the PCI operation. The level of N-terminal pro-B-type natriuretic peptide （NT-proBNP） and cardiac troponin I （cTnI） were measured. The changes of left ventricular end-systolic diameter （LVESD）,left ventricular end-diastolic diameter （LVEDD） and left ventricular ejection fraction （LVEF） were observed. In addition,main adverse cardiac event （MACE） and the incidence of bleeding complication were compared in 24 hours and 30 days after PCI. Results Compared with the control group,NT-proBNP was significantly decreased in 1 week after PCI,and cTnI was significantly decreased in 24 hours and 1 week after PCI in the early group （P<0.01）. There were no significant differences in LVESD and LVEDD in 1 week after PCI between two groups （P>0.05）,but LVEF was significantly higher in the early group than that in the control group （P<0.05）. There were no significant differences in MACE and the incidence of bleeding between the two groups （P>0.05）. Conclusion Early administration of tirofiban before emergency PCI can significantly increase LVEF and improve heart function in patients with acute STEMI,furthermore,safety is good.