The present disclosure relates to the field of display technology, particularly, discloses a backlight assembly and a display device. The backlight assembly includes a light guide plate and a light source. The light guide plate has a first light exiting surface and a second light exiting surface opposite to each other, and a light incident side intersecting with the first light exiting surface and the second light exiting surface. The light source is located at the light incident side of the light guide plate. The light guide plate has a refractive index which decreases first and then increases in a vertical direction from the first light exiting surface to the second light exiting surface.