One of the most prevalent health problems is coronary artery disease which may cause pain and heart attack. Stent implantation is a non-surgical method to treat the coronary artery disease that can support arterial walls and reduce the risk of heart attack. Utilizing finite element analysis to study the mechanical characteristics of this device is an efficient way to modify the design of stent and its performance. The main aim of the present work is to investigate the expansion characteristics of a certain stent as it is deployed and implanted in an artery containing a plaque, and try to reach to a model close to a real condition of stent implantation. A bi-linear elasto-plastic material model for stent and hyperelastic material models for balloon, artery, and plaque have been assumed. This model includes the internal pressure of blood. Stress distribution, outer diameter changes, and bending are investigated. A commercially available software has been used.