Collaborative Filtering (CF) technique has proved to be one of the most successful techniques in recommendation systems in recent years. However, traditional centralized CF system has suffered from its shortage in scalability as their calculation complexity increases quickly both in time and space when the record in user database increases. In this paper, we propose a decentralized CF algorithm, called PipeCF, based on distributed hash table (DHT) method. We also propose two novel approaches to improve the scalability and prediction accuracy of DHT-based CF algorithm. The experimental data show that our DHT-based CF system has better prediction accuracy, efficiency and scalability than traditional CF systems. Categories and Subject Descriptors H.3.3 [Information Storage and Retrieval]: Information Search and Retrieval?information filtering; H.5.3 [Information