Current spatial decision support systems (SDSS) in manufacturing environments, which are mostly CAD-based, have many drawbacks and thus may make less effective and efficient spatial decisions. GIS-based SDSS can overcome those drawbacks and support decision-making in a much effective manner. Unfortunately, there is little research on GIS-based SDSS in a manufacturing environment. This thesis study focuses on a systematic approach to the development of GIS-based SDSS in a manufacturing environment. By using Trane China as an example, the prototype of Trane China SDSS (TCSDSS) is developed by adopting the unified software development process. The TCSDSS prototype contains eight object modules, which incorporate ArcGIS embedded models, ArcGIS feature data, and MS Access attribute data, to support decision-making in Trane China. The benefits from the use of the TCSDSS prototype that have been found include its spatial analysis, network analysis, and 3D analysis functions besides the improvement on communication and efficiency. It is also found that the newly developed GIS software packages such as ArcGIS 8.3, with the enhanced drawing functions, can provide enough adequate precision level required by facility layout.