Inclusion Criteria:  Age ≥ 18, ≦75 years old, weight ≥45kg, gender is not limited. Diagnosis of acute ST-segment elevation myocardial infarction (both of the following) (A) Ischemic chest pain lasting more than 30 minutes; (B) Ecg indicates ST-segment elevation ≥ 0.1mV in 2 or more limb leads, or ST-segment elevation ≥ 0.2mV in 2 or more adjacent chest leads; Time from onset of persistent ischemic chest pain to randomization ≤12 hours; Coronary angiography and/or PCI are expected to be performed within 2 hours of r-SAK thrombolysis.  Exclusion Criteria:  Non-ST-segment elevation myocardial infarction; STEMI with cardiogenic shock; active bleeding or bleeding tendency, including Ⅲ, Ⅳ period history of retinopathy, retinal hemorrhage, gastrointestinal tract and urinary tract hemorrhage (1 month), ischemic stroke happened over the past 6 months, transient ischemic attack (TIA) happened over the past 6 weeks, hemorrhagic stroke in the past, unexplained platelet count < 100 x 109 / L or Hemoglobin <100g/L; Having a history of central nervous system trauma or known intracranial aneurysm; Recent (within 1 month) severe trauma, surgery or head injury; Suspected aortic dissection, infective endocarditis; Recent history of puncture which difficult hemostasis by compression (visceral biopsy, compartment puncture); Long-term use and/or current use of anticoagulant drugs; Hypertension not well controlled ≥180/110mmHg; Having severe hepatic and renal impairment (ALT, AST, γ-GT > 2.5 times the upper limit of normal value; Cr > 1.5 times upper normal); Known allergies to r-SAK; Pregnant, breastfeeding or planned pregnancy women and male patients with family planning; Patients who have participated in other clinical trials in the past 3 months; Having a history of myocardial infarction or CABG; Having taken antiplatelet drugs after pain onset, such as clopidogrel, prasugrel, cilostazol etc; Other reasons that patients considered unsuitable for inclusion by researchers.