以Gnutella为代表的非结构化P2P系统通常会呈现复杂网络结构，针对其度分布服从幂律分布的特点，提出一种基于节点簇的搜索策略。该策略利用节点簇来存储系统中文件的索引，通过将搜索过程限制于节点簇内部来提高搜索性能。然后，基于数学模型的理论分析给出了搜索性能上下界的数学描述。实验结果表明，搜索性能与簇的阈值c密切相关；c的取值范围灵活性很大，此时稀有文件的搜索效率至少可以提高一倍以上，文件索引的传输和存储代价可以减少一个数量级。该策略不需要学习全局拓扑知识，具有稳定并且易于实现和部署的优点。

In order to simplify the complex structure of unstructured peer-to-peer （ P2P） networks such as Gnutella,a node cluster-based random walk search algorithm is proposed. In this algorithm,node clusters are used to store file indices,and the search process is constrained in node clusters to improve the search performance. Afterwards,the upper and lower bounds of search performance are formulated based on the theoretical analysis of the mathematical model. Experimental results indicate that the search performance of the proposed algorithm is closely related to the cluster threshold c,and that,at the suggested value of c,namely half of the maximum degree in the system,the success rate of searching rare files increases by at least 250% and the transfer and storage cost decreases by one order of magnitude,as compared with the common random walk algorithm. The proposed algorithm is of the advantages of low storage cost high search efficiency as well as ease realization and deployment.