The standard manual wheelchair is commonly found in hospitals, rehabilitation centres, senior housing and airports for allowing patients, people with physical disabilities or elder people to move. In this thesis, a CAD model of the standard wheelchair is first obtained. Then, an optimization design is carried out based on this model. A sliding seat is designed to facilitate people moving by themselves from the wheelchair to any chair close by. On the other hand, a reclining backrest is also designed to make users feel more comfortable. Computer Simulations are performed to evaluate this design under static and dynamic conditions. A displacement range for the sliding seat in which the wheelchair will not overturn is determined. The optimization design shows significant improvements that can conveniently be introduced on the mechanical wheelchair in order to make it more useful and comfortable to the users.