This paper aims to propose our study of system model design for a Web 3D disabled access GIS. The disabled access GIS provides the disabled with information on barriers and barrier-free modifications in consideration of their abilities and psychologies. We model the system for web-based accesses. It enhances its reusability and mash-up capability. Our model clearly divides database access, server-side service and client-side user interface. We implemented desktop client and mobile phone client to examine the model.