This paper focuses on how to model grid resource and locate grid resource using efficient and scaleable protocol under a grid environment. A mathematic model of grid physical resource space and logical resource space is built based concept of virtual organization. Then, a mathematical method based the binary equivalent relation is presented to divide grid physical resource space. Then, this paper proposes the concept of grid resource domain, and introduce a fully decentralized grid resource locating protocol based it from aspects of the overlay network of grid resource domains and query routing protocol among different grid resource domains. On the other hand, in order to propagate query among information nodes within given grid resource domain, this paper presents informed search protocol based bloom filters. Our resource locating protocol can enhance the query success rate and recall rate, and avoid too much unnecessary query messages.