Unstructured peer-to-peer (P2P) file-sharing networks are popular in the mass market. As the peers participating in unstructured networks interconnect randomly, they rely on flooding query messages to discover objects of interest. Empirical measurement studies indicate that the peers in P2P networks have similar preferences, and recently proposed unstructured P2P networks intend to organize the participating peers in a small-world (SW) fashion by exploiting the knowledge of contents stored in peers. As existing algorithms for constructing SW-based unstructured P2P networks may not precisely reveal the object sharing patterns, the resultant networks thus may not perform searches efficiently and effectively by exploiting the common interests among peers. In this paper, we suggest a novel P2P network formation algorithm to construct SW-based unstructured networks. We validate our proposal in simulations with an empirical data set, and the simulation results prove that our proposal greatly outperforms existing algorithms in terms of search efficiency and effectiveness.