P2P network attracts more and more attention as an alternative to publish or access to information, because of its advantages in scalability, decentralization and self-organization. While a lot of research has been focused on semantic query routing in information system over P2P network, little work concerns if semantic query routing can satisfy the requirement of semantic information retrieval, and to what extent the query routing mechanism can provide the information semantically related to users’ query. In this paper, we study the application of semantics in traditional information retrieval and information system over P2P network; The gap between semantic information retrieval and semantic query routing is demonstrated; Finally, the challenge of semantic information retrieval over P2P network is presented.