With the development of P2P systems,it is widely applied in Internet,the lookup distributed data object particularly.So a simple way of the lookup based on P2P network system is presented.Supposed in the steady state,an fixed N-node P2P system,a given key is mapped onto avirtual identifier ring using a consistent hash function,every node on the identifier ring lookups the mapping of the given keys according to the routing information. On the basis of the analyzing and researching of the way,the way is correct and efficient. At the same time, it occupied a little memory.