The Internet of Things (IoT) has been developed tremendously due to advancements of a variety of technologies, such as sensors, wireless communications, and computing. There are a lot of applications of IoT, which range from common home and personal appliances to large-scale and safety critical systems [1, 2]. The recent Dyn event has raised our concerns about the security of IoT. On October 21, 2016, the Mirai IoT botnet was utilized by attackers to launch high-impact distributed denial of service (DDoS) attacks against the Dyn DNS service, which caused an extended Internet outage. The Mirai IoT botnet is composed of Internet-enabled digital video recorders (DVRs), surveillance cameras, and other Internet-enabled embedded devices. An IoT device is at great risk of security vulnerabilities, because there are many distinctions between IoT and traditional Internet devices. For example, the number of IoT devices is much greater. Nodes of IoT are limited in resources and dedicated, diversified communication protocols are used in IoT, and so on. Some of these differences weaken the ability of IoT nodes to protect themselves. IoT is connecting smart things, such as intelligent devices and sensors, to the Internet. The data collected by smart things is sent to a central cloud-based service that processes all the gathered data and shares these data with users [3, 4]. Combining the IoT concept and industrial wireless sensor networks (IWSNs) may reap the full benefits of the IoT. The Industrial IoT (IIoT) is going to reform manufacturing by enabling manageable IIoT devices to interact with each other and to join different parts of manufacturing by using networks. On one hand, IIoT profits from IoT. On the other hand, it also bears the same security risk as IoT. Although IoT and IIoT have different architectures, they face common network and host security threats due to limited resources. Traditional ways of preventing DDoS attacks are insufficient to satisfy security requirements. Security guarantee is essential to IIoT. Due to distributed sensor nodes, actuators, and machines connected to form the production system, it becomes nontrivial to ensure the authenticity and data confidentiality of the system [5]. Thus, new ways must be found to defend against DDoS attacks. In this article, a multi-level DDoS mitigation framework (MLDMF) for IIoT is proposed, which includes the cloud computing level, fog computing level, and edge computing level.