In this study, the current situation and characteristics of the three-dimensional (3D) geographic information system (GIS) and the large-screen display system are analyzed. Then, with a general comprehensive display platform as an example and the digital-twin visualized display of Nanning City as the subject, a large-screen visualization strategy based on the 3D GIS is proposed from the perspectives of spatial information scene design, expression object selection, page layout, platform color design, symbol design, chart design, and dynamic effect design. The system architecture and key technical points of such platforms are expounded in view of this strategy. A platform of this type is developed to provide a reference for similar visualization cases.