rates, and can even interrupt the function of devices. Recently, 2D transition metal carbides and nitrides (MXene) have demonstrated exceptional shielding ability, [1a,b,e,3] due to their high EM absorption, lightweight, high strength, and ease of manufacture. [2,4] Ti 3 C 2 T x is a typical MXene material, and T x represents the surface terminated parts, such as O, OH, or F. [2a,5] Its intrinsic metallic nature [6] combined with abundant surface termination and a laminate architecture contributes to achieving a high EM shielding performance. [1a,7] In each layer, the incident EM waves are partially reflected due to the high intrinsic electrical conductivity of MXene, and the remaining waves are then partially dissipated due to the interaction of the EM-dirven electrons with the MXene lattice defects. [8] This process can be repeated in the laminate architecture of MXene until the penetrated EM waves are competely absorbed. [9] This EM shielding performance can be further improved by introducing porous structures with partial oxidation in annealed MXene, but the observed increase cannot be fully explained within the framework of existing shielding theories. [1b] These phenomena imply that there must be other dissipation channels in addition to classical reflection and absorption of EM waves.One possible explanation is the plasmon-induced EM absorption, which has been observed in MXene [10] as well as metals [11] 2D metal carbides and nitrides (MXene) are promising candidates for electromagnetic (EM) shielding, saturable absorption, thermal therapy, and photocatalysis owing to their excellent EM absorption. The plasmon resonances in metallic MXene micro/nanostructures may play an important role in enhancing the EM absorption; however, their contribution has not been determined due to the lack of a precise understanding of its plasmon behavior. Here, the use of high-spatial-resolution electron energy-loss spectroscopy to measure the plasmon dispersion of MXene films with different thicknesses is reported, enabling accurate analysis of the EM absorption of complex MXene structures in a wide frequency range via a theoretical model. The EM absorption of MXene can be excited at the desired frequency by controlling the momentum (e.g., the sizes of the nanoflakes for EM excitation) as the strength can be enhanced by increasing the layer number and the interlayer distance in MXene. For example, a 3 nm interlayer distance can nearly double the plasmon-enhanced EM absorption in MXene nanostructures. These findings can guide the design of advanced ultrathin EM absorption materials for a broad range of applications.