Abstract: How much service performance of searching and transmitting is provided by P2P network for a concrete resource? How much success ratio and recall ratio of resource’s searching of existing P2P network is?Rare research is deepened about those questions.For unstructured P2P network，thecalculating method of service performance of concrete resource is provided，and the success ratio and recall ratio of resource’s searching are analyzed.It concludes recall ratio of resource’s searching is only related with topology character of P2P network itself，and not related with resource’s quantity.Otherwise，when TTL≥4，mostly searching process can reach higher success ratio and recall ratio.

Key words: Peer-to-Peer, service model, performance analysis

摘要： P2P网络针对具体资源能提供多少搜索和传输服务能力?资源搜索的成功率和查全率是多少?目前，针对类似问题的研究还较少发现。针对非结构化P2P网络，建立P2P网络排队模型，研究P2P网络针对具体资源提供的搜索服务能力、传输服务能力以及资源搜索成功率和查全率；研究发现：资源搜索的查全率只与P2P网络属性相关，而与具体资源的数量无关；当TTL≥4时，可以保证多数情况下资源搜索的成功率和查全率。

关键词: 对等网络, 服务模型, 性能分析