**Abstract**

At present, various cyberattacks based on Botnet are the most serious security threats to the Internet. As Botnet continue to evolve and behavioral research on Botnet is inadequate, the question of how to apply some behavioral problems to Botnet research and combine the psychology of the operator to analyze the future trend of Botnet is still a continuous and challenging issue. Botnet is a common computing platform that can be controlled remotely by attackers by invading several noncooperative user terminals in the network space. It is an attacking platform consisting of multiple Bots controlled by a hacker. The classification of Botnet and the working mechanism of Botnet are introduced in this chapter. The threats and the threat evaluation of Botnet are summarized.

**Keywords:** Botnet, threat evaluation, Botnet classification, Botnet threat
