Abstract: The mechanism model of macro-scale command and control（C2）activity process description, the conceptual connotation of PREA loop is redefined from physical domains, information domains to cognitive domains. In physical domains, the evolutionary law of micro system is followed, four states of system are defined: design, construction, tunning and evaluation. In information domains, the process of gradually dissipating the fog of war is followed. Four kinds of situation are defined: inpredicatable deductive situation, predictable situation, real-time situation and retrospective situation. In cognitive domains the law of the gradual convergence of the decision-making of commander is followed, then four kinds of decision-making methods are established according to four situations: careful decision-making based on intention and deductive situation, prudent decision-making based on pre-plan and predictable situation, rapid decision-making based on rules and real-time situation, and effect-based conversion decision-making based on effects and retrospective situation. The connotation of the four stage of PREA are summarized including: stratagem, deployment, control and evaluation of situation. The comparative analysis of the PREA loop and the OODA loop is done, reflecting the two different thinking and philosophies of the East and the West. The PREA coop emphasizes the continuity and stability of the entirety, while the OODA loop emphasizes quickness and intervention.