To reduce the energy consumption of wireless sensor network used for emergency monitoring, the design realizes an event driven based adaptive routing algorithm. Based on connected dominating set, this algorithm constructs cluster tree which is rooted from sink node, when new event takes place, a local structure is constructed in that region to quickly transfer message to sink node through cluster tree, so as to avoid a wide range of flood routing in the network. In addition, it proposes periodical replacement strategy of cluster head, which avoids too fast consumption of cluster head node energy, effectively balances the energy consumption of network nodes, and thus efficiently extends the lifecycle of network and enhance the robustness.