A Wireless Sensor Network consists of many sensor nodes built in sensing, data processing, and communicating components, which has found its wide use in health, military, and security.Each node with limited energy supports sensor operations, on-board signal processing, and communication with neighboring nodes.So, Power conservation is a challenging accomplishment for wireless sensor network because each sensor node's power recourses are limited.How to extend the lifetime of the network should be carefully considered in designing wireless sensor network.In this paper we proposed an energy efficient dynamic energy management technique for target tracking in Wireless Sensor Network, We utilize PSO algorithm and duty cycling technology in order to let sensors that perform tasks be in the active state and all other sensors are in the sleep state.The proposed mouthed is useful for manage sensor nodes to extend network lifetime.