Based on researches on TEEN protocol and combined the characteristic of monitoring emergences system, an event-driven hierarchical routing algorithm (TEEN-PE) has been proposed to reduce the energy consumption in the monitoring system of emergences and prolong the lifetime of the wireless sensor networks (WSN). TEEN-PE has solved the problems of the difficulty in determining the initial number of the optimal clusters and the asymmetrical distribution of cluster in TEEN protocol. And to improve the communication balance of the networks on times and space, the algorithm is taken into accounts the factor of the residual energy of the nodes and the distance of the node to the base station during the phase of cluster formation and communicates among clusters. The algorithm can effectively reduce energy consumption and prolong the lifetime of the networks. It is proved by simulated in NS-2, and the simulation results show that TEEN-PE has an advantage over TEEN protocol on nodes survival and energy consumption.