GMS(GEOMania Millennium Server) is an open spatial database management system which proudly boasts combined technologies of database, client/server technology and geographical information technology. GMS is a result of pure domestic application technology that has been developed to provide platforms for NT and UNIX servers while being able to be connected with the common clients. It also guarantees much higher efficiency than existing plug-in products or systems of other GIS packages by making it possible to develop GIS and maintain lowcost repairs. Such combined technology dramatically shortens the developing period and sets developers free from the costly time consuming work of complex system organization. GMS(GEOMania Millennium Server) provides a flexible and expandable 3-tier architecture making is easily possible to adapt to various application fields by hosting Enterprise GIS to a wide range of on-line GIS systems.