中文摘要：

负载均衡是P2P系统在设计时需要考虑的公平性问题之一,本文针对DHT网络中文件在节点问分布不均匀的问题,提出了一种基于树型结构的负载均衡方案，针对P2P网络中节点的性能差异和相同节点上文件的差异提出对于文件的负载度量准则，并根据此准则对一些热门文件按照树型结构复制方案进行分块复制，该复制方案具有维护简单、扩展性好、负载更分散的特点．仿真结果表明本方案大大改善了网络的性能，有效地进行了负载均衡．

英文摘要：

Load Balancing is one of the fairness problems in P2P system. However, files are not always equally distributed in DHT networks. In order to solve the problem,this paper propose a tree-based load balancing method. In this method,first a measurement metric for load of files is put forward, considering differences of nodes＇ performance and those of files. Then some heat files are replicated tree-based according to the metric. It＇s scalable and easy for the nodes to maintain the tree＇ s information. And the load is very dispersive. This method is proved to be effective by simulation.