Abstract: Objective To compare the effectiveness and safety of ticagrelor versus clopidogrel in acute coronary syndrome (ACS)combined with diabetes mellitus (DM) after percutaneous coronary intervention (PCI). Methods PubMed, Cochrane Library, CBM, Wan fang database and China National Knowledge Internet were used for searching literatures on the comparison of effectiveness and safety of ticagrelor versus clopidogrel in ACS combined with DM after PCI before June 2018. The quality of the articles was assessed according to the method of Cochrane manual standard. Results A total of 15 articles were included in this Metaanalysis, covering 2 231 patients. The results of this Meta-analysis showed that the incidences of major adverse cardiac events (MACE), myocardial infarction and stent thrombosis of ticagrelor group were lower than those of clopidogrel group (OR=0.40, 95%CI: 0.29-0.53, P=0.000; OR=0.53, 95%CI: 0.30-0.95, P=0.034; OR=0.30, 95%CI: 0.16-0.56, P=0.000). There was no statistically significant difference between the two groups in the incidence of bleeding events (OR=1.23, 95%CI: 0.88-1.72, P=0.227). However, the incidence of dyspnea events of ticagrelor was higher than that of clopidogrel (OR=4.2, 95%CI: 2.39-7.38, P=0.000). Conclusion Compared with clopidogrel, ticagrelor has obvious advantages in reducing the incidences of MACE, myocardial infarction and stent thrombosis, without improving the incidence of bleeding events, while it may increase the incidence of dyspnea events.