An image display device includes a flat panel display, a lens array layer, and a microstructure dynamic optical layer. The lens array layer is located at a side of a display surface of the flat panel display, and can adjust light field. The microstructure dynamic optical layer is located at the side of the display surface of the flat panel display, and can be switched to have a microstructure function or not to have the microstructure function. When being switched to have the microstructure function, the microstructure dynamic optical layer can modulate a direction of light emitted from the flat panel display. Accordingly, the image display device can display a 3D dimensional image floating in mid-air, and enables a user to see the 3D dimensional image at an oblique viewing angle. The image display device can be used in different ways according to practical applications.