I. Introduction
The nodes of WSNs are small volume, low cost, and have ability to carry out knowledge. They are able to collaborate to complete a variety of monitoring and control tasks. WSNs is a kind of intelligent autonomous system, and this makes their application become very broad [1]. They are used in military, intelligent transportation, environmental monitoring, health and other fields widely. However, because of the impact of volume and environment, the energy of network is not inconvenient to add. Therefore, planning multi-hop path of WSNs reasonably, balancing network loads, and ultimately maximizing the entire network life-time become more and more important.