Sirolimus-eluting stent (SES) has been proven to improve outcomes in patients with significant coronary artery diseae(> 70% lumen diameter narrowing). But, acute coronary syndrome may occur in those with intermediate lesions(50%-70% lumen diameter narrowing), and the effect of SES in these patients remains unclear. Here the investigators hypothesize that application of China-made SES may improve the clinical outcomes in these setting.

Inclusion Criteria:

• age 18-80 years old
• both gender
• native coronary lesion
• narrowing 50-70%
• vessel size 2.5-4.0 in diameter

Exclusion Criteria:

• without informed consent,
• ST elevation myocardial infarction within 7 days,
• left main lesion,
• by-pass graft,
• restenosis
• abnormal liver function before randomization,
• active hepatitis or muscular disease,
• impaired renal function with serum creatinine level > 3mg/dl ,
• impaired left ventricular function with LVEF < 30%,
• participate in other studies.