Abstract: An approach for analyzing the relationship among botnets was presented.Several botnet communication characteristics were extracted,including the amount of data flows within a botnet,the number of packets per data flow,the payload of communication and data packets in the master hosts.Statistical similarity functions of botnet characteristics were defined.Based on the cloud model and the defined statistical similarity functions,the analysis model of botnet relationship was build,and the similarities of botnet characteristics were synthetically evaluated.The analysis experiments were conducted based on a simulation network environment.The experimental results show that the presented method was valid and efficient,even in the case of encrypted botnet communication messages.The result is better than the research production in the report on the interrelated research achievements.