Abstract: In condition of limited space domain and time domain, the essence of effective multi-function effect of RF integrated system is to realize multi-function coordination and high-efficiency operation of the system. However, the bottleneck restricting cooperative and efficient operation of the system is the available electromagnetic resources under specific space-time conditions. The efficient utilization of electromagnetic resources depends on electromagnetic synergy which is to seek the optimal solution of constructing electromagnetic synergy self-organization structure in multiple dimensions of time, frequency, space and energy according to the task requirements and limited conditions, and determine the driving mode of orderly operation of the self-organization structure in specific task space-time. Electromagnetic synergy serves the integration of multi-functional RF integrated systems, which can effectively utilize and manage the electromagnetic environment of the battlefield and effectively improve the operation efficiency of the multi-functional RF integrated system. This paper discusses the key points of electromagnetic cooperation from three aspects: the bottleneck of multi-functional RF integrated system, the concept of electromagnetic cooperation and the method of electromagnetic cooperation. This paper is expected to provide a feasible technical approach for the fusion operation of multi-functional radio frequency integrated system.