文件污染是当前P2P文件共享系统普遍存在的问题，极大的降低了系统的可用性。P2P文件共享系统和生物免疫系统一样，都是高度分布、自适应和自组织的。利用向量空间相似度赋予投票权重，采用自适应的信誉阈值判断文件可信性，建立了基于人工免疫的防污染对象信誉机制来进行邻居节点集的选取，以改进系统可用性。仿真实验表明，系统具有很高的识别精确度，能够以低通讯代价很好的抑制污染文件在网络中的传播。

The problem of file pollution is prevalent in p2p file sharing system nowadays. The pollution reduces the availability of system sharply. As the same as natural immune system, p2p file sharing system is also highly distributive, self-adaptive and self-organized. Vector space similarity is computed to weight the votes collected from other peers. Self-adaptive reputation threshold scheme is adopted to estimate the file authenticity. Artificial immunology based anti-pollution object reputation mechanism is established to select neighbor peer set and improve the system availability. Simulation results show that the system can distinguish between good and polluted files accurately and thwart the proliferation of pollution in the network with low communication cost.