Aim To investigate the changes of biomechanical properties of carotid atherosclerosis in rabbits and its connection with the content of collagen.Methods 30 male Japanese White rabbits were randomly divided into control group(n=6) and the surgery group(n=24).The control group was fed by normal diet,but the surgery group was fed by high-cholesterol diet and treated in left carotid artery by air-drying.Meanwhile right carotid artery was treated as sham group.At 2,4,8 and 12 week after operation,the biomechanical properties were measured on a tensile-testing machine.The Elastic modulus,the strength failure and the peak load was measured,meanwhile the degree of artery stenosis was showed by DSA.The stenosis rate,mean integra optical densities(IOD) of media collagen were calculated.Results The typical atherosclerotic plaque showed in surgery group.Following development in degrees of the atherosclerosis,the intima showed proliferation and media showed atrophy and became thin,a mass of collagen tissue proliferated and filled in the smooth muscle cell.Atery elastic modulus and stiffness was increased and atery compliance was decreased.Statistic analysis showed significant difference at the 12 week group,compared with sham group and 2,4 and 8 week group after operation,but it showed no such significant difference at 2 week group after operation,compared with sham group.Conclusions At the early carotid atherosclerosis,vessel showed positive remodeling.Elastic modulus decrease to adapt to the new mechanical condition.But following development in degrees of the atherosclerosis,the content of the artery wall collagen increases,the vessel wall elasticity decrease and stiffness increases.The vessel occurs negative remodeling.It suggests that the interventional treatment be in difficulty.