VRML (Virtual Reality Modeling Language) is a programming language with promising effectiveness in describing cyberspace because of its real-time expressive power for 3D objects via the Internet. Concerning its 3D design, CAD tools can support static feature developments effectively, but currently, developments of dynamic features such as animation cannot be supported well, thus the tasks of debugging, testing, and behavior parameter adjustment become difficult. A program slicing technique is effective for such tasks. Thus we have applied it into VRML programs. In this paper, we studied VRML program structures and features, then proposed various kinds of dependency in VRML, and also proposed a VRML slicing approach based on such dependency. Finally we implemented several support tools.