Embodiments of the present invention disclose a backlight and a display device, to reduce the number of LEDs in a backlight, save costs, while avoiding dark areas appearing on the screen, so as to ensure display effect. The backlight comprises a first light guide plate and at least one light-emitting diode assembly, and the light-emitting diode assembly is located on one side of the first light guide plate. The light-emitting diode assembly comprises a second light guide plate, at least one light-emitting diode and a reflective film, wherein the at least one light-emitting diode is located on at least one side of the second light guide plate, and the reflective film is located on at least one side of the second light guide plate.