To cope with the high complex properties and high costs of measuring the metamaterial absorber in the free space, in this paper we experimentally discuss the absorption characteristics of four kinds of metamaterial absorbers based on different electric resonators in a closed X-band (8-12 GHz) rectangular waveguide. The measured results indicate that the four metamaterial absorbers exhibite similar absorption characteristics and mechanisms in comparison with the results obtained from free space. Further, in this paper we also discuss the rectangular wave matching terminal applications based on the proposed four metamaterial absorbers. And the results show that these new rectangular waveguide matching terminals can possess the advantages including the compact dimensional size, flexible controllability of the operating frequencies, and low costs. Moreover, the matching frequency bands of the novel terminals can be realized by designing the broadband metamaterial absorbers.