Polylecetrolyte brushes form when linear polymers with ionize-able monomers are grafted densely into a surface by one end. The steric and electrostatic repulsion between ionize-able monomers stretch the chains in the direction perpendicular to the surface. This feature makes Polyelectrolyte brushes ideal for many technological applications, such as, lubrication in synovial joints of mammals as aggregan, stabilization of cells movement as Glycol, smart 1 surfaces for bio-compatible implants, controlled targeted drug delivery, etc. 2 Polyelectrolyte brushes have been the subject of many researches for decades due to their complexity. Theoretical physicists have used many theoretical tools to tackle this sophisticated system, however, none of them apparently have been successful up to the present. In this article, I present my approach to the Polyelectrolyte brushes through density functional theory (DFT) framework, which is a powerful theoretical tool to tackle many body systems.