A backlight unit includes: a back plate including a bottom wall and a side wall around a periphery of the bottom wall; a lamp strip including a substrate and lamp beads on the substrate; a light guide plate on a side of the bottom wall provided with the side wall, the lamp strip being on a first side wall of the side wall, and light emitting surfaces of the lamp beads being opposite to a side surface of the light guide plate; and a position limiting and fixing structure between the light guide plate and each of the back plate and the lamp strip, for limiting and fixing a position of the lamp strip relative to the light guide plate to keep a gap between the light emitting surfaces of the lamp beads and a light incident surface of the light guide plate unchanged during turn-over of the backlight unit.