To store, access, process and show the spatial geoinformational data easily in the microcomputer environment, the 3D model must be determined. The paper introduces 3D vector topology model in the Visualization System; first, to confirm entity characters in the System based on the information characters of three-dimensional entity in the world. Second, to study and define the 3D entity using the object-oriented approach, and to draw the conclusion-there is only polyhedron geometric class in the 3D vector topological model. Furthermore, it is discussed how to build a 3D vector topology model in the Visualization System. Third, to present what constitutes a polyhedron, which relationships exist among the geometric elements, and how to represent the 3D geometric elements in the Visualization system using an example.