A backlight unit (10) and a display device are provided. The backlight unit (10) comprises a light guide plate (101), and a light source (102), a first reflective film (101), and a second reflective film (104). The light source (102) includes a plurality of LEDs (1021) uniformly arranged. The first reflective film (103) is disposed correspondingly on a backlight side of a region opposite to each of the LEDs on the light guide plate (101); The second reflective film (104) includes at least one first sub-reflective film (1041), the first sub-reflective film (1041) being disposed correspondingly on a backlight side of a region opposite to a gap between two adjacent LEDs on the light guide plate (101). A reflectivity of the first reflective film is less than a reflectivity of the second reflective film, and a distance between the light guide plate (101) and the LEDs is less than a distance between an intersection of light beams emitted by two adjacent LEDs and the LEDs, and, a width of the frame of the display device can be reduced.