A display device is provided. The display device includes a display panel and a backlight module. The display panel includes sub-pixels and a light-shielding layer disposed around the sub-pixels. A reflective nano-grating is disposed on one side of the light-shielding layer near the backlight module. The backlight module provides a backlight source for the display panel, and the backlight source is converted into a polarized light in the display panel. The reflective nano-grating is used to reflect at least one part of the polarized light emitted toward the reflective nano-grating back to the backlight module for recycling.