Recently, ontology-based intelligent information retrieval systems, aiming to further improve the retrieval performance and intelligence by using ontology, have become one of the hottest topics in the domain of intelligent information retrieval systems. This paper presents an overview of the field of ontology-based intelligent information retrieval systems from a process-oriented perspective, including the system framework, ontology knowledge acquisition and use, key technologies, and evaluation. The prospects for future development and suggestions for possible extensions of the ontology-based intelligent information retrieval systems are also discussed.