Backlight module and display device

The embodiment of the invention provides a backlight module and a display device, the backlight module comprises a back plate, the back plate comprises a bottom plate and a side plate connected with the bottom plate, and the bottom plate and the side plate jointly form a containing space; the diffusion plate is positioned in the accommodating space; the limiting assembly comprises a first limiting piece and a second limiting piece, and the first limiting piece is located between the side wall of the diffusion plate and the side plate and is configured to limit the diffusion plate in the first direction and the second direction; the second limiting piece at least comprises a part located on the side, away from the bottom plate, of the diffusion plate, and the second limiting piece is configured to limit the diffusion plate at least in the thickness direction of the backlight module; the optical film is located on the side, away from the bottom plate, of the diffusion plate.