Abstract: The underlying doctrinal guidance for joint domain-wide command and control（C2）concept is the OODA loop, but this doctrine does not cover the key activities of domain-wide C2, including operational planning, operational management, operational assessment. To resolve this paradoxical phenomenon, this paper adopts a completely different research approach, i.e., exploring the joint domain-wide C2 mechanism model by using the system C2 process mechanism （planning-readiness-execution-assessment, PREA loop）, and the main innovations include: using the PREA loop as a guide to establishing the general process of cross-domain operational C2 activities; establishing the joint all-domain C2 mechanism model based on the cross-domain C2 process mechanism - The nesting and interaction of each closed-loop process is established from the four links of joint domain-wide operational planning, deployment preparation, operation monitoring, and evaluation conversion; third, the operational management structure and information security model of joint all-domain C2 is established around the core of multi-domain multi-loop nesting. And taking the maritime composite formation as an example, using the machine model of all-domain C2, we analyze the multi-domain multi-loop nested symbiotic and concurrent asynchronous operation framework of maritime composite formation and design the command and control mode of maritime composite formation based on this framework. Through the exploration of joint all-domain C2 mechanism based on PREA loop, it is found that PREA loop is feasible for joint all-domain C2 concept study; PREA loop is complete for joint all-domain C2 process mechanism description; all-domain C2 mechanism model-multi-domain multi-loop nesting can be used to guide the C2 activities of maritime synthetic formation and system construction application.