Network measurement is the foundation for the in-depth research on P2P network. It's a prerequisite for the P2P protocol design, shared content searching, situational awareness as well as research on the security of P2P network. In structured P2P network with decentralized peer to peer relationship, high dynamics and unpredictable instantaneous disturbance, achieving highly accurate and near-complete information retrieval is much more difficult. This paper formalizes the search (or crawl) process of structured P2P network, studies the relationship between the node's route spreadness in the whole network and the query response rate in the midst of crawling, derives some improved search strategies from the knowledge of historic measurements and characteristics of specific P2P network, and proposes a improved search method with much lower bandwidth consumption, fast crawling speed as well as relatively high coverage of nodes in structured peer-to-peer network. KAD network is among the few of structured P2P networks that are extensively deployed. This research mainly concentrates on KAD network and develops a search tool called KadCrawler, upon which large amounts of measurements and analysis are conducted. The result shows that the proposed method is both feasible and effective. Lastly, an analysis on the topology and phenomenon of ID repetition reveals that KAD network has changed significantly over the years.