A back light assembly includes a light guide plate (LGP), a light reflecting member (LRM), at least two lamps, and a receiving container. The LGP includes a light incidence face having a width that is a first distance, a light reflecting face for reflecting a first light, and a light exiting face for emitting the reflected first light as a second light. The LRM covers the light incidence face to form a receiving space defined by the LRM and the light incidence face. The at least two lamps are disposed in the receiving space and spaced apart from each other by a second distance. A sum of diameters of the two lamps and the second distance is longer than the first distance. The receiving container receives the LGP and the LRM, where the LRM includes a chamfer disposed at an edge, the chamfer enhancing a reflection efficiency.