Three-dimensional (3D) city building models with its related information is an important part in the construction of Digital City and Digital Earth, and has been becoming a kind of staple resources on the web. Based on the characteristics of 3D building model, a service-oriented architecture and Web service technology for 3D city building models is discussed. A structure detail based building model is studied and a novel approach named 3D transparent building model service is presented in this paper. The aim of the approach is that 3D city building models can be used as a kind of data resource services on the web, and can also exist independently with numerous different web applications.