Abstract: Based on characters of wireless sensor networks,the nodes around the sink use up their energy much faster than other nodes, which forms the energy holes problem. How to avoid energy problem and to prolong network period is hot in wireless sensor networks. Now methods of solving energy problem are mostly balancing the network's load. We concluded the methods of this problem from five parts, these are energy control and power control, data compress and mixture strategy, node's non-uniform distribution, dynamic nature and increasing sink's number, and cluster algorithm.What is more, we analysed the advantage and disadvantage among these five, and proposed the research direction.

Key words: Wireless sensor networks,Energy holes,Sink node