We designed an edge-lighting light guide plate (LGP) based on a micro-prism structure for liquid crystal display. Its top and bottom surfaces have micro-prisms, and a layer of high reflection film is coated on the bottom surface. The principle of the LGP was analyzed. The optical simulation tool ASAP was used to calculate the apex angle and height of the micro-prism on the top of the LGP, the apex angle of the micro-prism on the bottom of the LGP and the emitting angle dependent luminous flux of the LGP. By adjusting the width of micro-prisms on the bottom, the LGP achieved uniform luminance. A 12-in LGP based on a micro-prism structure as an example was designed. The results proved that the LGP based on a micro-prism structure is thin and simple with uniform luminance and high efficiency.