 This is a prospective, multicenter, randomized controlled clinical trial comparing different doses of rosuvastatin in patients with acute coronary syndrome post drug-eluting stents implantation. In total, the investigators plan to recruit 80 patients with acute coronary syndrome but no acute ST-segment elevation myocardial infarction participating in the study. After signing informed consent form, the patients will be randomly assigned into high dose rosuvastatin and low dose rosuvastatin groups 40 cases in each group by a computer generated random sequence table on a ratio of 1:1. Patients in the high-dose group will be prescribed rosuvastatin calcium of 20mgd at least 6 months post index procedure, while patients in low dose group will have rosuvastatin calcium of 10mgd, also at least 6 months. Additionally, all patients will receive dual antiplatelet therapy oral aspirin 100mg qd, clopidogrel 75mg qd or ticagrelor 90 mg bid. Clinical follow up telephone or out-patient follow-up will be scheduled at 30 days, 6 months, 1 year, 2 years and 3 years. Optical coherence tomography examinations will be performed at 6 months. Neointimal hyperplasia, stent strut coverage and thin cap fibroatheroma are primary observational parameters. Multi-slices CT are optional pre-post-procedure and at 3 years follow-up. All clinical data will be collected and managed by statistical center, clinical endpoint adjudication committee. All imaging modalities data will be collected and analysed by an independent imaging core laboratory. 