Abstract: OBJECTIVE To investigate the efficacy and safety of dual antiplatelet treatment(aspirin+ticagrelor, DAPT) combined with different doses of tirofiban on diabetic patients with ST-segment elevation myocardial infarction(STEMI) receiving emergency percutaneous coronary intervention(PCI). METHODS One hundred fifty eight diabetic patients with STEMI undergone emergency PCI were randomly divided into three groups:53 patients in the DAPT group(group A), 52 patients with DAPT plus conventional doses of tirofiban group(group B), and 53 patients with DAPT plus one-half dose of tirofiban group(group C). In PCI, group B and C were injected intracoronally with tirofiban hydrochloride(10 μg·kg^-1). After PCI, group B was 0.15 μg·kg^-1·min^-1, group C was 0.075 μg·kg^-1·min^-1 continuous intravenous infusion for 24 h. Statistical analysis of the clinical data, coronary artery lesion characteristics, length of hospital stay and complications. RESULTS Compared with group A, thrombolysis in myocardial infarction 3(TIMI 3) blood flow and TIMI myocardial perfusion grade 3(TMPG 3) myocardial perfusion of patients in group B and group C after PCI was significantly higher(P<0.05), reinfarction during hospitalization, post-infarction angina, severe arrhythmia, the incidence of cardiac function above Killip Ⅲ level of patients in group B and group C after PCI was significantly lower(P<0.05). Severe bleeding and moderate incidence of bleeding in group B was significantly higher than that in group A and group C(P<0.05). Minor bleeding incidence of group B and group C was significantly higher than that of group A(P<0.05). CONCLUSION Emergency PCI for diabetes mellitus complicated with STEMI, one-half dose of tirofiba plus DAPT can effectively improve TIMI blood flow and TMPG myocardial tissue perfusion, reduce the occurrence of severe complications such as angina pectoris, re-infarction, severe arrhythmia and heart failure after infarction, and reduce the complications of severe hemorrhage.