Objective: To investigate the effect and safety of different antiplatelet regimens on elder patients undergoing PCI after 6 months. Methods: From April 2016 to April 2018, a total of 106 patients (over 70 years old) undergoing PCI after 6 months were enrolled and divided into clopidogrel group (n=36, aspirin 100 mg qd+ clopidogrel 75 mg qd), low-dose clopidogrel group (n=36, aspirin 100 mg qd+ clopidogrel 50 mg qd) and ticagrelor group (n=34, aspirin 100 mg qd+ ticagrelor 60 mg bid). All enrolled patients took aspirin 100 mg qd and clopidogrel 75 mg qd for six months. General clinical data of all patients were collected. Platelet aggregation rate (PAR) was detected at enrollment, one month and three months after enrollment. Hemorrhage and major adverse cardiac event (MACE) were recorded for six months. Results: Compared with before enrollment, levels of PAR in low-dose clopidogrel group were higher those that one month and three months after enrollment (P<0.05). Levels of PAR in ticagrelor group one month and three months after enrollment were lower than that of before enrolled level (P<0.05). Very few patients had PAR levels above 50% in clopidogrel group six months after enrollment, and PAR levels of all patients were below 50% in ticagrelor group six months after enrollment. A large number of patients had PAR levels above 50% in low-dose clopidogrel group six months after enrollment. There was no statistical significance of hemorrhage event among the three groups (χ²=1.301,P=0.624). Log-rank analysis showed that:there was a statistical difference in the cumulative incidence of MACE among the three groups during the 6-month follow-up (χ²=5.351,P=0.039). Conclusion: In elderly patients with PCI, the use of ticagrelor 60 mg bid to replace the traditional clopidogrel at 6 months after surgery has a better anti-platelet aggregation effect, with a lower incidence of MACE and no increased risk of bleeding.