Abstract: A method of transforming the engineer case library to the structural form-selection rules library and the case gene library is presented.The correlative relationships among the case space,the rule space and the gene space are setup.The exchanging form cases to the intelligent form-selection rules and genes are realized.A strategy is given so that the structural form judging-rules knowledge library is found from the case gene library.It provides the similar calculating method between gene vector and case and counter-case gene library,and establishes the method and process of knowledge discovery of the structural form selection library based in case gene library and genetic algorithm float code.A knowledge discovery software code based on the case gene library and GA is developed and the knowledge acquired from RC structure is also given.It is shown that this method can effectively acquire the rule knowledge library produced by structure forms from case gene library,and provide a new way and method for mining engineering ‘rich resources'.It resolves the ‘bottleneck' of knowledge acquirement and improves the quality and efficiency of structural form-selection.