With the development in network communication, the research and application of "virtual city" has become an important discussion item. The crucial point lies on how to set up a virtual visual model of city on Internet; it is the organic integration of computer science, information science, geosciences and system science. This text summarizes the basic conception of "digital earth/the virtual fictitious city", and probes into the technology of combining with Web on the basis of 2DVR, 3DVR and GIS. It develops the new emulation mode of the virtual urban system and key technology while developing the scheme wholly. This paper offers the interactive methods of the virtual world and outside world. The method of using the panorama, three dimensional model and active server pages technology to realize interactive network virtual city roam is studied and a running example is given. Using the system we can offer the visual brand-new technical support for urban planning, traffic for tourism, etc.