A light source module with two wavelengths that is adapted to generate laser beams different in wavelength. In the light source module, a hologram optical element (HOE) is used to allow a first laser beam generated at a first light source and a second laser beam generated at a second light source to progress along same path. The HOE diffracts the second laser beam to change a progressive path of the second laser beam into that of the first laser beam. The first light source generates the first laser beam having a different wavelength from the second laser beam generated at the second light source.