The disclosure provides a backlight module and a display device. The backlight module includes a light guide plate including a light emitting surface, a lateral surface, and a light incident surface disposed correspondingly to the lateral surface. The light emitting surface is connected to the lateral surface and the light incident surface. A light source is disposed correspondingly to the light incident surface and is configured to emit light toward the light incident surface. An optical film is disposed on the light emitting surface. A fixing component is disposed on the light incident surface or the lateral surface and is configured to fasten the optical film on the light emitting surface so that the optical film can be evenly expanded uniformly along a direction parallel to the light source after being heated.