Aim To investigate the expression of p27Kip1 in the atherosclerotic plaques of rats and fasudil hydrochloride intervention role. Methods 30 healthy male Wistar rats were randomly divided into three groups:normal control group,atherosclerosis group and fasudil group.Rats in normal control group were undertook fake sacculus proprius damage and then were offered normal diet.Rats in atherosclerosis group and fasudil group were given Vitamin D3 intramuscular injection first,then were suffered artery balloon injury and were fed with basic diet added cholesterol,sodium cholate,propylthiouracil,Vitamin D3 powder,lard.While rats in fasudil group were given the intraperitoneal injection of fasudil.After 9 weeks,all the rats were killed,the expression of Rho kinase and p27Kip1 protein in the vascular tissues were detected by immunohistochemistry method. Results The atherosclerosis group formed typical atherosclerotic plaque.Semi-quantitative immunohistochemical analysis showed that Rho kinase expressed in the normal vessel wall,and increased significantly in atherosclerosis group compared with that in the other two groups(P><0.01),Rho kinase expression in fasudil group also increased compared with that in normal control group(P><0.05).p27Kip1 protein expression in the normal vessel wall more,p27Kip1 protein expression in atherosclerosis group decreased significantly compared with that in the other two groups(P><0.01).p27Kip1 protein expression in fasudil group also decreased compared with that in the normal control group(P><0.05). Conclusion The expression of Rho kinase obviously increased and the expression of p27Kip1 protein obviously reduced in atherosclerotic lesions.Fasudil obviously inhibit vascular smooth muscle cell proliferation,inhibit the up-regulation of Rho kinase expression and down-regulation of the p27Kip1 protein in atherosclerotic lesions.