VRML(Virtual Reality Modeling Language) is a programming language with promising effectiveness in describing the cyberspace because of its real-time expressive power for 3-dimensional objects via the internet. Concerning its 3-dimensional design, kinds of CAD tool can support static features developments effectively. But currently, developments of dynamic features such as animation can not 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.