Spatial utilizatio plan has been established for all regions based on regional spatial planning map (Peta Rencana Tata Ruang Wilayah). Nvertheless, manay problems have been reported, where deviation between spatial utilization plan and actual utilization occured. The reason for this overlap is mainly caused by lack of reliable spatial information sysem. Exixting spatial information systems in Indonesia are characterized by the following conditions: 1) Public has difficulty to search and to access geospatial data distributed among various institutions. As aconsequence, people unable to verify potential overlap on spatial utilization in a certain region, 2) Un-organized geospatial data caused redundant effort on data collection. 3) Different geospatial data format prohibiting data sharing among institutions. Development of web based spatial information system is expected to minimize these problems. Observations, literature and regulation analysis were carried out to determine system requirements. Meanwhile, Unified Modeling Language (UML) Version 2.0 was applied for logical and physical modeling. To support interoperability of distributed access mechanism, open standard of Open Geospatial Consortium (OGC) web service was implemented. Distinct features of the systems are: 1) Sharing mechanism of distributed geospatial data using web map service, and 2)Overlay multi map layers on the fly without addtional deployment of commercial GIS software. Keyword: Geospatial Data , Spatial Planning, System Requirement, Interoperability, UML, Web Map Service.