In order to solve the thickness dependence of plasma absorption of electromagnetic waves and further reduce the backward radar scattering cross section (RCS) of target, we designed a novel composite structure of a metasurface and plasma. A metasurface with three absorption peaks is designed by means of an equivalent circuit based of an electromagnetic resonance type metamaterial absorber. The reflection absorption by the composite structure is numerically and experimentally verified. The finite integration method was used to simulate the composite structure of finite size to obtain the radar cross section. The experimental measurements of electromagnetic wave reflection are conducted by the vetor network analyser (Keysight N5234A) and horn antennas, etc. The research shows that the absorption capacity of this composite structure is substantially improved compared to either the plasma or the metasurface, and it is more convenient for application due to the low plasma thickness requirement and easy fabrication.