A backlight module includes a light guide plate, a light source, a first prism sheet, and a second prism sheet. The light source is disposed on a light incident surface of the light guide plate. The first prism sheet is disposed on a side of a light exiting surface of the light guide plate and has multiple first prism structures facing the light guide plate. The second prism sheet has multiple second prism structures facing the light guide plate. An included angle between an extending direction of the first prism structures and an extending direction of the second prism structures is greater than or equal to 85 degrees and less than or equal to 95 degrees. An included angle between the extending direction of the second prism structures and the light incident surface is greater than or equal to 85 degrees and less than or equal to 95 degrees.