With the rapid development of cloud computing, Linux cluster is used widely with the advantages of low cost and good scalability. This paper presents a method of design and implementation of Linux cluster monitor. Some information, such as the CPU and memory usage, are collected from /proc virtual file system on every node at regular intervals. After being filtered, these information are sent to monitor server via socket. The overall design scheme of monitor is first described in the paper. It is composed by information management server process, which is run on the management node and collecting processes, which are run on every node. Then their design framework and key techniques are introduced.The collector is composed by three modules that is information collection, information processing and information transmission. These modules are realized by three threads. The thread pool technology is used by information management server, which receives the transfer request sent by collector. Proved by practice, this system can well satisfy the real-time monitoring of Linux cluster performance.