A light source assembly includes a light source unit, a light collecting unit, a light separating unit and a light converting unit. The light source unit generates a first light beam having a first color and a first optical path. The light collecting unit has a light entering side and a light exiting side and is configured to collimate and condense the light beam incident on the light entering side. The light separating unit is disposed on an area between the light entering side and the light exiting side of the light collecting unit for reflecting the first light beam entering from the light entering side of the light collecting unit. The light converting unit absorbs the first light beam reflected from a light separating unit and generates a converted light beam having a second color.