Objective： To evaluate the safety and efficacy of antiplatelet therapy of ticagrelor on patients suffering from acute ST segment elevation myocardial infarction undergoing primary percutaneous coronary intervention.Methods: In the study, 96 patients suffering from acute ST segment elevation myocardial infarction onset within 12 h undergoing primary percutaneous coronary intervention from May to October in 2013 were randomly divided into ticagrelor group (n=48) and clopidogrel group (n=48) by using the method of random number table. Ticagrelor and clopidogrel antiplatelet treatment were used before and after operation. Their baseline data, coronary artery disease characteristics, platelet count, adenosine diphosphate(ADP)-induced platelet inhibition rate by thrombelastograph after 5 days of treatment, the major adverse cardiovascular events of the follow up for 6 months and bleeding complications were observed and compared in the two groups. Results:  The differences between the two groups of patients with their baseline data, the features of coronary artery lesions, platelet count before and after 5 days of treatment had no statistical significance (P>0.05). ADP induced platelet inhibition rate ［(80.2±10.7)%］ after 5 days of treatment in ticagrelor group was significantly higher than that in clopidogrel group ［(75.3±12.1)%, P<0.05］. The two groups of patients were followed up for 6 months, 8 cases of major adverse cardiovascular events occurred in clopidogrel group, 2 cases of major adverse cardiovascular events occurred in ticagrelor group, and there was significant difference between the two groups (P<0.05). The two groups (7 cases of 48 patients in ticagrelor group vs. 3 cases of 48 patients in clopidogrel group) had no statistically significant difference in bleeding complications (P>0.05).Conclusion: Antiplatelet therapy of ticagrelor on patients suffering from acute ST segment elevation myocardial infarction undergoing emergency PCI has good efficacy and safety.