Objective To investigate the efficacy and safety of low-dose ticagrelor in the treatment of acute coronary syndrome (ACS) in the elderly patients with chronic renal insufficiency (CRI). Methods A total of 148 consecutive inpatients (aged≥75 years) with ACS and CRI were enrolled in the study, who were admitted to the Department of Cardiology of the 986^th Hospital of the PLA Air Force from October 2016 to February 2017. Patients were divided into low-dose ticagrelor group (LD group; 45 mg/once, twice/d; n=52) and standard-dose ticagrelor group (SD group; 90 mg/once, twice/d; n=96). Thromboelastography (TEG) was performed 3 days after oral administration. The 2 groups were compared in the inhibition rate of platelet aggregation (IPA) induced by ADP, and the incidence of major adverse cardiac and cerebrovascular events (MACCE) and hemorrhage events during a follow-up of 12 months. The data were analyzed using SPSS statistics 19.0. Student′s t test or χ² test was performed for comparison. Results IPA induced by ADP in the SD group was higher than that in the LD group [(83.4±2.5)% vs (67.3±4.7)%, P＝0.043], but there was no significant difference with IPA was fewer than 50% between 2 groups[13.5%(7/52) vs 5.2%(5/96),P＝0.219]. No significant difference was found between the 2 groups in the incidence of MACCE at month 12 [19.2%(10/52) vs13.5(13/96),P=0.476]. The incidence of massive hemorrhage in the LD group was significantly lower than that in the SD group [9.6%(5/52) vs 24.0%(23/96), P＝0.033]. Conclusion Low dose of ticagrelor can be as effective as standard dose in antiplatelet action, reducing the risk of bleeding events and maintaining a balance between ischemia and hemorrhage.