The invention discloses a 3D displaying device and a control method thereof and relates to the technical field of 3D displaying. The problem that a 3D displaying device with a touch screen function is thick is solved. The 3D displaying device comprises a liquid crystal raster placed on a liquid crystal displaying module. The four corners of an electrode of the liquid crystal raster are each provided with a detecting end point for detecting a current value. The 3D displaying device further comprises controllers connected with the four detecting end points in a signal mode. The controllers are used for computing contact positions according to the current values of the four detecting end points. The touch screen function of the 3D displaying device is achieved.