知识库系统是一种专门存储、管理大量知识的机构。文章以可拓学的理论和方法为指导 ,提出可拓知识表示法和可拓知识库系统的特点与构架。给出了可拓知识表示的形式化语义 ,其基本单元是知识物元 ;阐述了矛盾问题求解的形式表示 ,其核心是问题的物元模型 ,通过可拓算子把不相容问题转化为相容问题 ;相关方式推理是可拓知识库系统推理机的特点 ,是传统规则推理的推广。可拓知识库采用可拓知识表示方法 ,是传统知识库的一个超集 ;可拓知识库系统由目标库、条件库、公用知识库、分类知识库、推理机与知识库管理系统组成 Knowledge base system is a specialized storage, management of a large number of knowledge institutions. Based on the theory and method of extenics, this paper puts forward the characteristics and framework of extenics knowledge representation and extension knowledge base system. The formal semantics of the extension knowledge representation are given. The basic unit is the knowledge matter element. The formal representation of the solution to the problem of contradiction is expounded. The core of the problem is the matter-element model. The problem of incompatibility is transformed into Compatibility problem; the related method reasoning is the characteristic of the extension knowledge base system reasoning machine, which is the promotion of the traditional rule reasoning. Extension knowledge base adopts extension knowledge representation method, which is a superset of traditional knowledge base. Extension knowledge base system consists of target base, conditional base, public base, classified base, inference engine and knowledge base management system