Abstract: This paper presents the design principle and realizable approach for the intellectual data model of the geographic expert system. With the frame network structure of knowledge, the author describes the entity units of geo-environment, and links the expression of expert knowledge at different levels with the pointer so that it becomes the frame network from knowledge to semantics. Also, the author expresses expert knowledge with extended R-F relational model based on intelligence, and discusses organizational structure of the knowledge base in the system and the design principle of inference engine. The data structure can be used to realize an integrated description for geographic entities and their interrelations, and the knowledge base of the system can be operated simply and easily with the model, and therefore, the inference mechanism can be assuredly realized. Taking Urumqi river basin as a test region, the author expounds the expression approach of the expert knowledge involved in the planning and decision concerning the rational use of land in the basin as well as the basic rules of expert knowledge expression and the organization models of expert knowledge in the system. Furthermore, the author also discusses the design principles and organization method of the inference rules and the inference algorithms of inference engine in the system.

Key words: knowledge expression, frame network structure, intellectual data model