It is the foundation of developing virtual prototype to construct assembly model. On the basis of that the advantages and disadvantages of the existing assembly model are pointed out through studying on relational models separately, a new virtual assembly model based on scene graphics technology of extensible group node, which is suitable to personal computer, is brought forward. Using this new scene graph technology, virtual prototype can be constructed easily and quickly. Besides that virtual assembly can be solved well, several kinds of subsequential simulation functions are considered synchronously, which include virtual manufacturing, working process, and visualization in engineering analysis.