With the increasing seriousness of electromagnetic pollution in civil applications and national defense, current radar absorbing structures (RASs) with narrow absorption performance and high density are inadequate to meet the demands for excellent electromagnetic absorption performance. Therefore, achieving broadband absorption capabilities in RASs across the frequency range of 2 to 40 GHz is a pressing issue and a topic of significant interest. This review article summarizes the multi-dimensional design of broadband RASs by integrating materials, structures, and manufacturing processes, promoting the application of novel materials in three-dimensional structures through advanced manufacturing processes in the future. Meanwhile, the multi-scale absorption mechanism, including the micro-scale absorption attenuation mechanism and macro-scale absorption resonance, has been discussed. Finally, the major challenge of current RASs and their relatively new frontier has been discussed, highlighting their potential for diverse applications across multiple fields.