Radome is an important telecommunication and structural component of radar system. If carbon fibers filaments are mixed into the radome accidentally during manufacturing process, it may cause local ablation failure of the radome. Now the heating mechanism of carbon fibers in electromagnetic fields and their impact on the radome are not clear. Therefore, the article intends to explore and study it through finite element analysis (FEA) method. Firstly, the finite element model construction technology of composite plates containing carbon fiber filaments were researched. Secondly, the heating mechanism of composite plates, which had different specifications of carbon fiber filaments, under electromagnetic fields was analyzed. Finally, the corresponding ralationship between the heat generation of carbon fiber filaments and failure modes of composite plate, such as discoloration and ablation, were researched through experiments. The relevant research results have a guiding role in the structural design, production process and fault analysis of radome.