A Lamp module, which includes a metal holder frame that defines a longitudinal open chamber and transverse mounting slots across the longitudinal open chamber, LEDs that are respectively mounted in the transverse mounting slots and have a respective top metal frame fastened to the top wall of the metal holder frame for quick dissipation of heat, light guides mounted in the longitudinal open chamber of the holder frame and respectively perpendicularly attached to the LEDs, and reflectors respectively embedded in the light guides for reflecting light in one direction.