Abstract: Objective: To understand the role of AngⅡin the formation and progression of atherosclerosis, the effects of AngⅡon proliferation of VSMC and the modulation on the promoter activities of human α2（Ⅰ） procollagen gene were studied. Methods: 1.Smooth muscle cells derived from SD rat were primary cultured and subcultured. Different concentrations of AngⅡ（10^-8 mol/L、10^-7 mol/L、10^-6 mol/L）were added into the plates to co-incubated with the cells. MTT method was used to detect the cell proliferation after 24, 48 and 72 hours. 2.Cells were transient transfected with pCOLH 22.4 and pCOLH 21.6 containing –2.4kb and –1.6kb of 5’flank sequence of human α2（Ⅰ） procollagen gene, fused to CAT reporter gene by FuGENE Transfection Reagent. The effects of AngⅡ10 -7 mol/L on the plasmid were determined by CAT-ELISA. Results: 1. AngⅡcould accelerate the proliferation of VSMC with dose-dependent. 2. AngⅡ can enhance the promoter activities of human α2（Ⅰ） procollagen gene. Conclusion: These data indicate that AngⅡcan accelerate the proliferation of VSMC and enhance the expression of human α2（Ⅰ） procollagen gene and accelerate the formation and progression of atherosclerosis.