Abstract: Theories and models about processes and mechanism of command and control (C2) with its background and scope of application are summarized. Relationship between mechanism and scale of C2 is proposed, which embodies on processes and mechanism of C2 with di erent diverse scale military systems (such as time scale, space scale, and scale in military force, et al.). The di erence includes layout of C2 closed loop feedback, style of commanding decision, object and content of controlling, et al. The application of classic theory —OODA loop in C2 area is in micro-C2, which is single platform command real time confrontation. New theories and models about processes and mechanism of C2 are required in macro or mid-scale military force.