Abstract: In view of the current development trend and theoretical research of the metaverse, this paper redefines the conceptual connotation of the metaverse. The origin of the metaverse can be traced back to digital data, and its technological source is various digital data generation technologies. According to two topological dimensions, such as the field of action of the digital form and the inter-domain nature of the interaction between the virtual and the real world, the metaverse can be divided into four types of staged forms: pure digital world, digital twin world, virtual-real co-construction world and virtual-real collaborative world. Putting the metaverse in the overall evolution process of the digital form, we found the evolution mechanism between its four development forms. That is, the pure digital world is closely related to the traditional cyberspace and has become the first choice for metaverse innovation, and the digital twin world focuses on the industrial real world. The virtual-real co-construction world integrates the structures and functions of the pure digital world and the digital twin world, and the virtual-real collaborative world is an advanced form of the virtual-real co-constructed world which is driven by the innovation of human digital concepts. This paper clarifies the conceptual connotation, form development and evolution mechanism of the metaverse, and provides a theoretical basis for the subsequent industrial policy formulation and the construction of the governance system of the metaverse.