Abstract: Objective: To explore the anti-platelet effects and safety of double dose of clopidogrel in acute ST-segment elevation myocardial infarction patients after percutaneous coronary intervention(PCI). Methods: Eighty acute ST-segment elevation myocardial infarction patients with PCI were randomly divided into the treatment group and control group(40 cases each group). The control group were treated with 100 mg aspirin and 75 mg clopidogrel once a day by oral. The treatment group were treated with 100 mg aspirin once a day and 75 mg clopidogrel twice a day for 1 month, then changed to 75 mg clopidogrel once a day by oral. After a month of treatment, the platelet aggregation rates in two groups were observed. The incidence of cardiovascular events in two groups were analyzed after 1 year of following up. Results: The difference of the platelet aggregation rate between two groups after 1 month of treatment was statistically significant(P<0.05). The differences of remyocardial infarction, cardiac mortality and incidence of stent thrombosis between two groups after 1 year of following up were not statistically significant(P>0.05). Conclusions: The treatment of acute ST-segment elevation myocardial infarction patients PCI with double dose of clopidogrel can decrease the cardiovascular events.