150 STEMI patients planned for emergency PCI were randomized to three groups, Group 1:received atorvastatin 80-mg loading dose before PCI then followed by 40-mg daily for one month and a maintenance dose of 20-mg qd thereafter(n=50); Group 2:received atorvastatin 40-mg qd after PCI for one month and a maintenance dose of 20-mg qd thereafter(n=50); Group 3: received atorvastatin 20-mg qd after PCI (n=50).Before PCI,all subjects received oral administration of aspirin 300mg and clopidogrel 300mg.Levels of creatine kinase,CK-MB(creatine kinase-MB),were measured to estimate myocardial damage degree.HS-CRP(high sensitivity C -reactive protein),NO(NO synthase),SAA(Serum amyloid A) were measured at preoperation 1 hour,postoperative 24 and 72 hours,7days after PCI. To compare echocardiography changes among three groups.Patients enrolled in the study need to receive follow-up survey which was carried out by clinical doctors.Hence,MACEs were analyzed during 6-month follow-up.So, the aim of our study is to evaluate the clinical significance of loading dosage of atorvastatin therapy and analyze the mechanism underlying it.