Abstract: In this paper, a vote based cluster head election mechanism is proposed.Which makes the nodes vote others whose energy are larger than themselves, meanwhile the ballot can't be forward.This method insures only the nodes have more neighbors and remaining energy can get more ballots.At the same time, the cluster head number must be chosen according to network energy consumption.These methods overcome deficiencies of cluster number and cluster head selection mechanism in LEACH protocol.Simulation results show that the method can be applied to library environment monitoring and achieve the desired purpose.