We propose a new and effective Light Guide Plate, called Empty Chamber Fresnel Lens Light Guide Plate (ECFL-LGP), to provide the merits of thin, lightweight, low-cost and high effect of light rays guiding for a medium or large LED-sourced Edge Lighting Backlight Module. It consists of a simple Empty Chamber and two sets of linear irregular Fresnel lenses. Due to the reasons that the structure of the Empty Chamber is simple and a Fresnel lens is thin and cheap, our ECFL-LGP will possess lower cost than the traditional hard LGP. On the other side, the irregular Fresnel lens in ECFL-LGP will be better than the traditional mesh-like dot about the effect of light rays guiding because its irregular linear groove angles can be evolved in terms of the optimization requirements of light rays guiding. As for the uniform problem of light rays guided to the LCD panel, we will design a double-deck linear irregular Fresnel lenses to act as a prismatic film according to the uniformity requirement. To overcome some problem caused by designing linear irregular Fresnel lenses, we propose an idea of dividing the designed Backlight Module into several sections to reduce the number of evolved groove angles, and dividing the design procedure into two stages: first, evolve two sets of linear irregular Fresnel lenses in the designed ECFL-LGP, then evolve four sets of linear irregular Fresnel lenses between the ECFL-LGP and the LCD panel. As a result, the thickness of the designed LED-sourced Edge Lighting Backlight Module will be 4.85 mm only (the LCD panel is not included).