Abstract: Setting up a cache system in large LAN can relieve the pressure of WAN interface and increase user's satisfaction.The traditional system store cache files with the local file system.Deploying the traditional system distributed could lead to high redundancy,resulting in a waste of resources.And deploying the traditional system centralized could lead to poor scalability,resulting in lack of performance.The cache system presented in this paper can store the cache files into HDFS.If the file got by user exists in the system,the user could get a redirect packet containing the file path nearest to the user.The HDFS Federation can use multiple NameNodes to extend HDFS capacity and reduce the load of single NameNode.The experimental result shows that this system can provide faster speed under extreme load.