The cyberspace upon physical space forms a new spatial structure to increase the influence on the urban fabric and the concept of space in architecture. Today, digital cities are being developed all over the world. By using a city metaphor, digital cities integrate urban information and create public spaces. However, human how to entry into the new emerging digital cities, to percept themselves in around cities, and then taking shape the recognition of digital city forms? How do digital cities directly connect to physical cities and become an imaginable city? Therefore, we argue that a new spatial analysis theory must be established for digital city, comparing with theories of spatial cognition, to find the explicitly spatial structures and relations in digital city upon physical city. This paper studied by the viewpoint of cognition in order to propose a prototype of metaphor of digital city.