A three-dimensional (3D) display device comprises a display panel and a grating disposed on one side of the display panel. The display panel includes a plurality of first display units and a plurality of second display units; the first display units and the second display units are alternately arranged in both a transverse direction and a longitudinal direction of the display panel. The grating includes a plurality of grating units arranged in parallel; an acute angle between each grating unit and the transverse direction of the display panel is a predetermined angle; and the grating is configured to present a first image displayed by the plurality of first display units and a second image displayed by the plurality of second display units to a left eye and a right eye respectively. The 3D display device can reduce the granular sensation in viewing a 3D image and hence improve viewing comfort.