This paper represents an attempt to fully describe how GISs are to be applied, the methodology of GIS application’ The first section examined the application background of the GIS development and evolution. It can be believed that advancement of the related technolo-gies, especially computer technology, has provided the possibility to build up more powerful GIS, while the application requirement has been vital motive to promote GIS development.The second section discussed the functionality of GIS and its main users.The databasefunction finds special use in the field of resources investigation and management, social and economic statistics, and the surveying and mapping agencies mostly utilize GIS to produce maps of high quality. Spatial analysis has been widely used by the research departments.GIS can be used as a tool box or methodology to solve the problems with spatial notion. As a tool, GIS can act like a spatial transaction processing system (ST PS), spatial management information system (SMIS)or spatial decision support system (SDSS). STPS uses only database function while SMIS adopts database function and spatial analysis and single/multiple models.SDSS is based on the CIS’ s database, spatial analysis and model-base technology . SDSS is model-driven while SMIS is data-driven.The scale of GIS application may fall into one of the following types, project GIS, depart-mental GIS, enterprise GIS.Most users pay more emphasis on the technology aspect, e. g. data structure and algorithms, not the on-going system.On the departmental GIS level, a practical system is to be developed for transaction processing and management. An enterprise GIS is generally a distributed system which is used as a decision-making tool.The last parts of the paper discussed the design and evaluation of the GIS systems. There is difference between building a applied system and prototype GIS. A applied system should be designed strictly by using life cycle or prototype-model design strategies. There is more advan-tage to combine these two design methods together. The system evaluation can be executed from the point of the economic and/or synthetic views.