Under the background of the concept and framework of the Digital Earth, the paper aims to study the architecture of a new spatial information network service model--G/S model. In order to improve the efficiency of geospatial data organizing, geospatial data managing,geospatial data describing and geospatial data transferring in the internet environment, as well as achieve the target of displaying, quering, analyzing and interactive operation of spatial information in the three-dimensional (3D) scene, the authors mainly discuss : the connotation of the G/S model; the basic framework of G/S model which is consist of HGML(Hyper Geographic Markup Language), Geo-browser and spatial information server which divides into spatial information base sever group and industry application data sever group, subsequently describes the principle, characteristics and technology system of its components respectively; an application prototype system based on G/S model. G/S model provides an effective way to reduce the network complexity and computational complexity of the spatial information, and provides an extensive application space for the spatial information technology.