Convenient, efficient and anonymous characteristic enables P2P network to own enormous users very quickly. However, how much service performance of searching and transmitting is provided by P2P network for a concrete resource? How much is the success ratio and recall ratio of resource's searching of existing P2P network? Rare research is deepened about those questions. This paper, for unstructured P2P network, provides calculating method of service performance of concrete resource; analyzes success ratio and recall ratio of resource's searching, and by experiment simulation, discusses the influence of resource's popularity, Peer's quantity, initial number of objected resource, Peer's average degree and TTL value to success ratio and recall ratio of resource's searching. We conclude that recall ratio is only related with topology character of P2P network itself but not related with resource's quantity. Otherwise, when, mostly searching process can reach higher success ratio and recall ratio.