The MATE study is a randomized, multicenter, open-label, investigator-initiated clinical trial aimed to evaluate efficacy and safety of sequential monotherapy of ticagrelor and clopidogrel in patients with acute coronary syndrome (ACS) after coronary intervention. Standard DAPT of aspirin plus ticagrelor will be given for the first 1 month after PCI. After 1 month, event-free subjects will be randomized at 1:1 ratio into receiving standard DAPT (DAPT) until 12months , or switch to ticagrelor monotherapy for another 5 months , and further de-escalated to monotherapy of clopidogrel for the last 6 months(SAPT).