The plastic deformation of stent is investigated in this study and the effect of atherosclerotic artery on the stent deformation is studied. The relationship between different stent structure parameters; i.e., stent thickness, length, slot length ration and final deformation are also discussed. The elastic-plastic finite element models is employed in the deformation and residual stress analysis. The materials of balloon, stent and artery were assumed to be linear elastic, elasto-plastic and nolinear-elastic Odgen model, respectively. A typical Palmaz type stent is analyzed. The deformation and stress distributions of the stent are simulated with the inflation and the deflation of the angioplasty balloon. Results indicate that the considering of the atherosclerotic artery may affect the calculated stent deformation and stress distributions significantly.