The invention provides a light guide plate which comprises a light incident surface, a light out surface and a bottom surface. The light out surface is perpendicular to the light incident surface and is connected to the light incident surface. The bottom surface is connected to the light incident surface relative to the light out surface. A plurality of first lattice points and a plurality of second lattice points are formed in the bottom surface, wherein the point diameter depth of each first lattice point is HF, the point diameter depth of each first lattice point is HS, and the difference between HF and HS is larger than 1 um and smaller than 15um. The invention also provides a light source module. Through the lattice points with different depths in the light guide plate provided by the invention, the scratch and wear of the light guide plate can be reduced, and the light source module provided by the invention has excellent optical taste.