Embodiments of the present invention provide a 3D display device, and the 3D display device, comprising: a display panel (1), configured to display an image; an optical element (2) and a liquid crystal lens (3), disposed to overlap each other and positioned at a light exiting side of the display panel (1), wherein the optical element (2) comprises a plurality of optical lens units (2a), the liquid crystal lens (3) comprises a plurality of liquid crystal lens units (3a), the plurality of liquid crystal lens units (3a) correspond to the plurality of optical lens units (2a) in a one-to-one corresponding relationship; when the 3D display device is in a 2D displaying mode, each of the plurality of liquid crystal lens units (3a) has an effect on light contrary to an effect on the light of each of the plurality of optical lens units (2a), and when the 3D display device is in a 3D displaying mode, the liquid crystal lens unit (3a) is configured to have a plane glass function. The 3D display device provided by the embodiments of the present invention can be switched between 2D and 3D displaying, and can reduce the crosstalk during 3D displaying and improve the display effect.