Certain aspects direct to a three-dimensional display device, which includes a display module defining a plurality of pixels, a barrier module, a sensing module, and a controller. For a viewer of the display module, the barrier module allows the viewer to perceives light emitted from the display module to form left-eye and right-eye views to form a three-dimensional virtual image. The sensing module generates sensing signals in response to detecting an object. The controller is configured to generate display signals for the display module to control the pixels, receive the sensing signals from the sensing module, and generate an object coordinate according to the sensing signals. In response to a display instruction, the controller controls the display module to display a three-dimensional virtual input device. In response to the object coordinate matching coordinates of an input region of the three-dimensional virtual input device, the controller generates an input command.