The display device includes an image display the screen of which includes a plurality of sub-pixels of three primary colors R, G and B for displaying a 2D image and a 3D image; and a DFD-PDLC lenticular lens array which includes a plurality of parallel DFD-PDLC lenticular lens elements, wherein the direction of the long axis of each of the DFD-PDLC lenticular lens elements is vertical or slant to the screen of an image display, the DFD-PDLC lenticular lens array is installed in front of the screen of the image display, the optical refractive index of the DFD-PDLC lenticular lens elements is variated under the drive of an external drive voltage V(f) to switch between the display of a 2D image and the display of a 3D image on the screen of the image display, wherein f is the drive frequency of the external drive voltage.