The invention relates to the technical field of display devices, and discloses a backlight and a display device. The backlight comprises a back plate, a reflector plate arranged in the back plate, a light source arranged on one side in the back plate, a reflector, and a diffuser plate. The light source is arranged on one side of a reflecting face of the reflector plate. The reflector is arranged on the side, opposite to the light source, in the back plate. The reflector is used for reflecting the light ray, irradiating on the reflector, of the light source to the reflector plate. The diffuser plate covers the light source and the reflector. According to the technical scheme, after the light ray irradiating through the light source irradiates on the reflector, the light ray is reflected to the reflector plate through the reflector and then reflected to the diffuser plate through the reflector plate, and then the purpose of light emitting is achieved. In the embodiment, the light source is arranged on one side of the back plate through cooperation of the reflector and the reflector plate, the thickness of the backlight is reduced accordingly, and then thinning development of the display device is facilitated.