Objective To investigate the dynamic changes of vascular adventitia and collagen distribution in the vein graft restenosis model, and evaluate the effects of adventitia and collagen distribution on intimal hyperplasia and vascular remodeling. Methods The pig autogenous vein grafts restenosis model from 18 longwhite pigs were created. 18 pigs were divided into 3 groups: 7th day group after operation, 30th day group after operation and 45th day group after operation according to animals harvested after surgery. The preoperative graft was as control group. According to HE and Masson staining slices, the vascular thickness, cell density, collagen distribution and vascular remodeling were investigated by histomorphometrical approach. Results In 7th day group after operation, the neointima formed and continuously thickened. The thickness and cell density of adventitia increased gradually, and the collagen of adventitia and neointima gradually increased, the luminal area gradually decreased after operation, but have no significant difference with control group（F=2.03,P=0.091）. The residual restenosis rate increased inversely（F=5.16,P=0.033）. Remodeling index and external elastic lamina area (EELA) slightly increased. In 30th day group after operation, the neointima thickened significantly, the thickness and cell density of adventitia reached the peak. There were a significant increase in the collagen of neointima, and the collagen of adventitia reached maximum. The luminal area and inter elastic lamina area(IELA) reduced distinctly as compared with 7th day group, the residual restenosis rate increased significantly（F=6.63,P=0.018）, but remodeling index and EELA decreased distinctly as compared with 7th day group after operation. In 45th day group after operation, the thicknessof neointima reached maximum, but the cell density of adventitia reduced distinctly compared with 30th day group after operation（F=6.91, P=0.015）. The collagen of neointima reached maximum, but the collagen of adventitia were smaller than those in 30th day group after operation, and there were some local fibrosis in adventitia. The luminal area, remodeling index, IELA and EELA reached minimum, but the residuum restenosis rate reached maximum. Conclusion Vein grafts restenosis is resulted by intimal hyperplasia and vascular remodeling. The thickness and fibrosis of adventitia and rearrangement of collagen are the important factors on intimal hyperplasia and vascular remodeling, which takes part in and accelerate the course of vein restenosis.