The invention refers to a diffusion plate and a backlight module having the diffusion plate. The diffusion plate comprises a plate-body and a plurality of pyramid-like structures arranged on a surface of the plate-body. Each pyramid-like structure has a bottom surface, a first convex portion and a second convex portion. The first convex portion and the second convex portion have different vertex angles, and therefore the pyramid-like structure can also be called as “pyramid-like structure with multiple vertex angles”. The pyramid-like structures with multiple vertex angles can increase the light splitting points, which can improve the light splitting effect of the diffusion plate. The light source of a single light-emitting diode can be divided into eight point-light sources (light splitting points) or more, which is double the number of light splitting points compared with the traditional pyramid structure with single vertex, and thus can greatly improve the light diffusion effect.