The development of virtual assembly platform (VAP) is discussed. It is a virtual environment on PC for training system that allows training supervisors to create training instructions and allows trainees to learn assembly operations. The models and the planning methods of assembly sequence and path are described. The virtual assembly simulation scenic framework is set up, and the level of detail technology is adopted to optimize the simulation scene. Moreover, in order to modify the assembly sequence and path timely and conveniently, and express exactly the components' position information and gesture during the assembly and disassembly course, a language code (V-code) that describes virtual assembly and V-function that describes correspondingly assembly operational classes are presented. Finally, human- computer interaction technology on 3D-mouse is explained. The simulation platform can help shorten the design cycle, improve design quality and reduce the assembly cost.