Abstract: 5G is applied to the military command field, bringing massive terminal ubiquitous interconnection and massive data realtime interaction, which will improve information sharing capabilities of command and control (C2) systems and C2 efficiency, promote the transformation of the staff, and open up new command areas, but at the same time bring data interaction security risks, transmission link security threats and information service security challenges. Focusing on the protection of C2 system access security, network security, user security, and application security, it is necessary to build a security framework for C2 systems based on 5G applications, and explore active security defense models that integrate security analysts and security equipment to enhance command network-wide security situation awareness and collaborative protection capabilities in C2 systems.