Digital library knowledge is knowledge management construct a new research field, is a comprehensive interdisciplinary subject area of knowledge services in libraries, for the construction of information systems has been compared, but the construction of knowledge still increasingly inadequate. In this paper, combing the Construction of Digital Library information and knowledge, knowledge conversion theory, based on the knowledge element as the focal point of knowledge building, knowledge building ontology reasoning for retrieval mechanism, ontology-based knowledge retrieval framework to build, on this basis calculated on the introduction of the similarity between ontology and relevance methods, to achieve ontology-based knowledge retrieval, and finally build the knowledge-based services for the functional analysis of knowledge.
