Digital sandbox projection system, divided into entity model and virtual image combination and the virtual two. Taking technology of the computer as the core of modern high-tech means to generate realistic 3D image model, with the aid of projection display equipment or other display device to display on the computer 3D or 4D graphics image model to the table. Cheng Hui and entity sand table interactive display demonstration to form a contrast, sand table demonstration effect more vivid, vivid.