Objective To study the deformation and mechanical characteristics during expansion process of vascular stent in realistic stenosis model, so as to provide scientific references for interventional treatment and stent design. Methods The carotid vessel model and plaque model of patient were built by using 3D reconstruction method, and the stent model with I-shaped link was established by using Pro/E; ABAQUS/Standard was used to simulate the radial expansion (the first stage) and radial contraction (the second stage) of the stent in real stenosis model, and a realistic model of blood vessel with plaque was also established to make contrast test. Results In the first stage, radial expansion of the stent was formed. The maximum contact area was generated between the outer surface of the stent and the inner surface of the plaque/arterial wall, and the maximum stresses on the stent, plague and arterial wall were 515.000, 2.482, 1.053 MPa, respectively. In the second stage, the radial contraction of the stent resulted in “dog-bone” effect. Many gaps between the stent and vessel wall was formed, and the maximum stresses on the stent, plague and arterial wall were 464.500, 0.954, 0.316 MPa, respectively. In contrast test, the maximum stresses on stenotic vessel and stent were 0.9, 414.1 MPa in the second stage. Conclusions Compared with the model in contrast test, the stenosis model differentiating the component of vascular tissues is more consistent with the real situation of stenotic vessels, by more truly showing deformation and mechanical characteristics of the stent and blood vessel. The stent causes the maximum damage to plaque and inner wall of blood vessel in the first stage, while “dog-bone” effect of the stent is an important influencing factor that results in the gaps between the stent, plague and blood vessel. These research findings may provide significant guidance for selecting stent in interventional treatment and improving stent design.