This paper introduces the background of Industrial 4.0 and through a comparison with the previous three industrial revolutions, emphasizing on the core idea which is put forward as the deep fusion of information systems and physical systems. Through the introduction of physical information fusion systems, we begin to analyze the interaction between the open interconnected network, its associated information along with the physical components, which makes the cyber-physics system face great security challenges. This paper presents research on Cyber Physics Department Security targets and the attack model of the unified system, giving an in-depth description about the security structure of layered information physical systems.