To solve the bottleneck on performance and low reliability of single core node, the cloud monitor system based on Peer-to-Peer (P2P) monitor network was designed and implemented. On the hardware deployment, the monitor nodes were capsulated in application containers and distributed on different racks to build P2P monitor network. By establishing distributed storage clusters with non-relational database, remote data access and backup were supported to improve system reliability. On the software implementation, it was designed hierarchically using combination method of push and pull to collect data, estimating trust degree of data, storing data in distributed nodes and managing hosts in cloud with threshold control and free host estimation strategies. Through the system tests, it was concluded that the system only accounted for 2.17% on average computing resource usage and its average responsive ratio on reading and writing requests per millisecond reached above 93%.The results indicate that the monitor system is superior on low resource consumption and high read/write efficiency.