A light diffusion sheet with high surface hardness and method of manufacturing the same is used in the backlight of liquid crystal display and is made by multi-player plastic co-extrusion technology, which can produce light diffusion sheet structure of a plurality layers. The structure is to propose at least a high surface hardness layer on the light diffusion sheet as producing backlight module with direct light of liquid crystal display so as to achieve the resistance to scratch. Therefore, it can prevent from the scratch caused by the hardness stuffs such as fingers, dust, module frame, and so on in the assembling, delivery, or packing processes, and further facilitate the mass production, reduce the manufacturing cost, and increase the yield ratio of assembling significantly.