Abstract: The expert system enables the optimization and full application of multiple-informations such as thecretic and practical knowledges, geophysical, geolcgical and geochemical informations. The model of knowledge acquirement in the system is set up with the resolvent and generalization used during the process of practical prediction. Five parts are involed in the knowledge expression model, i.e: graded knowledge expression, data processing, method expression and descriptions of controlling knowledge and uncertainty. The expert system based on the model inclueds knowledge base, data base, reasoning and learning parts,which is capable of theoretic and practical computations. It is applied to check computations of Chacshe structure in Qingtong depression, north Jiangsu.