In this article, the development of strong electromagnetic protection technology is reviewed in response to the strong electromagnetic environmental threats and protection reinforcement requirements faced by electronic information equipment in complex electromagnetic countermeasures environments, and the development prospects of strong electromagnetic system level comprehensive protection are proposed. Strong electromagnetic protection is a technical means to ensure that electronic information equipment is not damaged or destroyed in a strong electromagnetic environment. This paper analyzes the current focus and difficulties of electromagnetic protection from the coupling pathway of electromagnetic waves, and then analyzes and summarizes the development status of front door protection technology from three aspects: limiter technology, frequency filtering technology, and energy selection protection technology. Finally, the new electromagnetic protection technology is prospected from two aspects of new shielding materials and protective devices, and the system level electromagnetic protection is summarized from three aspects of integrated front and rear door protection, integrated field and road protection, and multi domain joint protection, which provides support for the electromagnetic protection reinforcement design of electronic information equipment in complex electromagnetic environment.