Objective To compare the bleeding risk in the over-70-year-old patients with coronary artery diseases treated by ticagrelor or clopidogrel after discharge from hospital. Methods Consecutive 597 elderly patients who were admitted to our department due to acute coronary syndrome (ACS) and underwent percutaneous coronary intervention (PCI) from Jan. 2014 to Mar. 2015 were enrolled in this study. According to their dual antiplatelet therapy, they were divided into ticagrelor group (n=99, treated with ticagrelor combined aspirin) and clopidogrel group (n=498, treated with clopidogrel combined aspirin). After 1 year’s follow-up, their bleeding risk was compared, and the risk factors of bleeding events were analyzed. Results The incidence of bleeding events was significantly higher in the ticagrelor group than the clopidogrel group (25.3% vs 14.5%, P=0.008), and significant difference was seen in the ratio of type Ⅰ bleeding events(P=0.015), but not in the type Ⅱ bleeding events (P=0.261) between the 2 groups. During the medication period, 263 patients underwent thrombelastography (TEG), including 77 cases from the former and 186 from the latter group. ADP-induced inhibition of platelet aggregation was significantly increased [(80.29±20.67)% vs (61.65±26.81)%, P<0.001], but ADP-induced maximum amplitude (MAADP) was significantly reduced [(25.28±14.28) vs (36.41±16.20) mm, P<0.001] in the ticagrelor group than the clopidogrel group. The ticagrelor group had significantly larger percentage of patients with MAADP <31 mm than the clopidogrel group (68.8% vs 40.3%, P<0.001), and these patients had obviously higher occurrence of bleeding events as well (24.5% vs 10.7%,P=0.037).Multivariate logistic regression analysis indicated that low body mass index (BMI;OR=0.910,5%CI:0.842-0.984,P=0.018) and being complicated with hypertension (OR=1.301,5%CI:1.036-1.635,P=0.024) were the independent risk factors of bleeding events in the ≥70-year-old patients with coronary artery disease in treatment of dual antiplatelet therapy. Conclusion The risk of bleeding events is higher when taking ticagrelor than clopidogrel in the elderly patients with coronary artery disease. And those with low BMI and hypertension are prone to bleeding events. Therefore, full consideration should be given to the risk factors of bleeding, and TEG monitoring should be carried out in the treatment of dual antiplatelet therapy in order to reduce the incidence of bleeding events.