[Objective]The paper proposes and forms an effective method of semantic knowledge acquisition through analysis, summary and experiment, in order to provide theoretical principle and possible technological route for the semantization of Institutional Repository.[Methods]Based on the contrastive analysis of methods of semantic knowledge acquisition both at home and abroad, the paper proposes a system framework of semantic knowledge acquisition for Institutional Repository, and sums up its key technologies for deep analysis and then takes the CAS IR GRID for an experimental study.[Results]This method can automatically and effectively acquire semantic knowledge information from data and entity relationship structure of relational database of underlying Institutional Repository and convert it into RDF triples for browse and search.[Limitations]To define a reasonable and effective mapping rule may need domain expert evaluation, more manual intervention and repeated experiments. The semantic knowledge acquisition and relevance study for the same entity object between different Institutional Repository is not involved in this paper.[Conclusions]This study may better help follow-up researchers and developers quickly understand and master the method and key technologies of semantic knowledge acquisition, then lay the foundations for enhancing knowledge service capabilities of Institutional Repository.