A display device and a display method thereof are disclosed. The display device includes a light guide module and a polarization layer, a light direction control section, a reflective layer sequentially disposed on a side of the light guide module. The light guide module includes a first major surface and a second major surface that are opposite to each other, and the first major surface includes first regions for emitting light and second regions, the polarization layer includes polarizers corresponding to the first regions, and the polarizers have a first polarization direction, and the light direction control section is configured to control light direction to adjust a passing amount of the light reflected by the reflective layer in the non-light exiting regions and make the light have a second polarization direction substantially perpendicular to the first polarization direction after passing through the light direction control section.