The invention relates to a diffusion sheet for a backlight module. The diffusion sheet comprises a base material layer and a diffusion layer, wherein the base material layer is made of a light-transmitting material; and the diffusion layer is laminated on the upper part of the base material layer and comprises an adhesive, nanoparticles and microparticles. Through the diffusion sheet with the structure, the rigidity of the diffusion layer can be improved so as to avoid the distortion and curling phenomena of the diffusion layer. In addition, the diffusion sheet has excellent diffusion effect according to the nanoparticle content of the diffusion layer, so that the defects of a light guide plate and an optical sheet can be effectively concealed or overcome and the luminance loss can be avoided.