Abstract: Due to the energy supply limitation in wireless sensor nodes, it's the primary challenge to optimize the networks' energy consumption and estimate network lifetime in wireless sensor networks (WSN). By analyzing the energy consumption features of WSN, this paper reviewed energy optimization strategies from the views of sensor nodes and networks,and then surveyed and concluded the WSN's energy modeling studies from different research perspectives;wireless communication based, state transition based, protocol stack based and others. Finally, this paper pointed out the future research should focus on the cross-layer energy optimization and the hardware and software integrated energy modeling techniques.

Key words: WSN, Energy consumption feature, Energy optimization, Energy model, Network lifetime