The architecture, technologies and implementation of the Shanghai city spatial information system for application and service, a SIG (Spatial Information Grid) based platform was introduced. In the system, there were ten categories of spatial information resources, including city planning, landuse, real estate, river system, transportation, municipal facility construction, environmental protection, sanitation, urban afforestation and basic geographic information data. In addition, spatial information processing services were offered as means of GIS Web Services. The resources and services were all distributed in different Webbased nodes. A single database was created to store the metadata of all the spatial information. A portal site was published as the main user interface of the system. There are three main functions in the portal site. First, users can search the metadata and acquire the distributed data by using the searching results. Second, some spatial processing Web applications developed with GIS Web Services, such as file format conversion, spatial coordinate transfer, cartographic generalization and spatial analysis are offered. Third, GIS Web Services currently available in the system can be searched and new ones can be registered. The system has been working efficiently in Shanghai government network since 2005.