A hierarchical semantic overlay network model HSON is put forward. In HSON, peers with resources of identical semantic are connected together to form SON. The semantics of SONs are associated with ontology concepts, and the hierarchical structure of ontology concepts is utilized to hierarchically organize all SONs. SONs with similar semantic are directly connected with each other. The structure of HSON is beneficial to query process. In contrast to flooding, queries are purposefully forwarded to destination SONs. Simulation results showed that hierarchical semantic overlay network model could improve recall, accelerate query routing process, and reduce the number of messages in the network.