Unstructured P2P networks usually adopt flooding algorithms for searching and locating resources in the network. However, flooding algorithms turn to produce a large number of query messages, thus, restrict the P2P networks' expansibility. By studying existing improvements on searching strategies, this paper proposes a new one based on the idea of Active Index Caching. The new algorithm actively publishes indices of new resources to other nodes in P2P networks. Experimental results show that the new algorithm outperforms the existing ones.