The optimal time for thrombolysis in myocardial infarction is within 12 hours of the onset of the infarction, and the earlier the treatment is received, the better the results are. Myocardial infarction is a disease in which the coronary arteries are blocked, leading to ischemia, hypoxia and necrosis of the heart muscle cells, which leads to the corresponding symptoms. The key therapeutic option is reperfusion therapy, which opens the occluded coronary artery within 3 to 6 hours, or at most within 12 hours, to reperfuse the myocardium and rescue the dying myocardium. Thrombolysis is a type of reperfusion therapy, and the optimal time for thrombolysis is within 12 hours after the onset of an infarction, and the earlier the time, the better the therapeutic effect. Contraindications include previous hemorrhagic stroke, intracranial tumor, recent active visceral bleeding, suspected aortic coarctation, and recent major surgical procedure. When myocardial infarction is suspected, prompt medical attention is recommended, and the earlier the treatment, the relatively better the prognosis.