Abstract: A 3D geometry model and storage structure that can describe multi part composite objects for simulation oriented virtual reality toolkit (SVRT) are presented. Use is made of boundary representation that includes multi level organization structure and multi level coordinate system in describing the geometrical object and binary tree data structure is used to store it. It is implemented with VC++ and OpenGL. The model and storage structure presented can describe the shape and visual characteristics (such as material, texture) of complex 3D objects accurately, and are easy to read, write and draw. It resolves the problem that a single part model cannot implemente the complex behavior of 3D objects, conforms the requirement of SVRT, and can also be used in general VR systems.