A backlight module and an anti-peeping display device are provided. The backlight module comprises a light guide plate, a lens and a light source. The lens is provided between the light source and the light guide plate, and light emitted from the light source is incident upon the light guide plate through the lens at a same incident angle; a light emission surface of the light guide plate is provided with protrusions, the light emission surface of the light guide plate is a total reflection surface except the regions where the protrusions are provided; a light emission surface of the protrusion is parallel with that of the light guide plate, a surface for performing a first reflection on light incident upon the protrusion is a total reflection surface, and the light incident upon the protrusion exit perpendicularly to the light emission surface of the protrusion after being totally reflected once.