Objective To study the safety and effectiveness of polymer-free sirolimus-eluting Nano stent in patients with unstable angina pectoris. Methods Three hundred and twenty-one patients with unstable angina pectoris were divided into Nano stent group(group A,n=157)and Endeavor resolute stent group(group B,n=164). The cardiovascular events were compared postoperative 12 months. The minimal intima cavity area and mini-mum bracket section area and neointimal area were compared postoperative 12 months by intravascular unltrasound (IVUS). Results There were 7 cases of cardiovascular events in group A and 6 in group B postoperative 12 months(P=0.727)and 2 patients in group A and 3 in group B were re-implanted stent because of restenosis post-operative 12 months(P=0.672). The neointimal area were(0.31 ± 0.11 mm2)in group A and(0.29 ± 0.12 mm2) in group B postoperative 12 months(P = 0.985). The minimal intima cavity area(P = 0.921)and the minimum bracket section area(P=0.934)were narrower postoperative 12 months than immediately after the operation in two groups. Conclusion With less cardiovascular events and being safe and reliable,the clinical effect of polymer-free sirolimus-eluting Nano stent implantation is similar to that of Endeavor resolute stent implantation.