Science of Security 2022 - In order to overcome new business changes that bring new security threats and challenges to many Industrial Internet of Things (IIoT) fields such as smart grids, smart factories, and smart transportation, the paper proposed the architecture of the industrial Internet of Things system, and analyzed the security threats of the industrial Internet of Things system. Combining various attack methods, targeted security protection strategies for the perception layer, network layer, platform layer and application layer are designed. The results show that the security protection strategy can effectively meet the security protection requirements of IIoT systems.