Abstract: For exploring how to establish a CIM′s basic platform to express and manage the entire 3D elements in urban space, this paper is taking the Tiexi New City of Shenyang as example. Through integrating 484 square kilometers of RS data, foundation of urban GIS data, BIM, underground pipeline information, underground survey information, urban perception information, and other multi-source information, by using Skyline as the 3D basic platform and Oracle as the database, with the adoption of SOA as system architecture and C# as programming language, BIM+GIS+IoT technology has developed for supporting the operation of Tiexi New City. Integration of underground and ground, outdoor and indoor, and static and dynamic has been achieved. The built CIM basic platform has achieved the digitalization of urban physical space of Tiexi New City for the infrastructure of modern city, which not only has provided important supports for the construction of the intelligent city of Tiexi New City, but also has provided a reference for CIM construction of other cities.