KD (D&K) (Synthesized Knowledge Discovery System based on Database and Knowledge Base Cooperating Mechanism) is first advanced in this paper on the basis of KDD (Knowledge Discovery System based on Database) and KDK (Knowledge Discovery System based on Knowledge Base). KD (D&K) is not simple addition of KDD and KDK but a new system with absolutely new character and essential development, which is distinct from KDD and KDK and includes them.Not only the generalized structural frame of control rules KD (D&K) acquiring method is proposed, but also the theoretical basis of its key technical problem-double-bases cooperating mechanism is discussed according to the original academic idea to restrict KDD by basic knowledge base.