The authors have been leading the "GEO (Global Earth Observation) Grid" project since 2005 which is primarily aiming at providing an E-Science infrastructure for worldwide Earth Sciences community. In the community there are wide varieties of existing data sets including satellite imagery, geological data, and ground sensed data that each data owner insists own licensing policy. The GEO Grid is designed to integrate all the relevant data virtually, enabled by Grid technology, and is accessible as a set of services. In this paper firstly we describe design principles of the GEO Grid that are determined based on accommodating users requirements for publishing, managing, and using data. Secondly, software architecture and its preliminary implementations are specified where we take the Grid computing and Web service technologies as the core components that comply with standard set of technologies and protocols.