A light source module includes a transparent element, a plurality of light-emitting devices, and a plurality of light diffusion micro-structures. The transparent element includes a transparent substrate having a light exiting surface and a bottom surface opposite to the light exiting surface, a plurality of first notches, and a plurality of second notches. The first notches are sunken at the light exiting surface. There is a reflection surface in each of the first notches. The second notches are respectively opposite to the first notches and sunken at the bottom surface. The second notches respectively have a light incident curve-surface. The light-emitting devices are respectively disposed beside the light incident curve-surfaces. Each of the light-emitting devices has a light exiting surface capable of providing a light beam. The light exiting surface is not conformal to the light incident curve-surface. The light diffusion micro-structures are disposed on the bottom surface.