The increasing electromagnetic (EM) radiation arise from the vast usage of EM techniques in civilian and military fields has spawned extensive concerns on scientific research with respect to EM wave absorbers. Nanomaterials, as a new type of nano-absorbing agent, have been investigated in detail over the recent years. This review article aims at elaborating the influence of component regulation and structural design on microwave absorption (MA) performance. Combined with the experimental efforts towards the development of nano-absorbers, the relevant absorption mechanisms are also discussed. In addition, from a prospective point, only focus on the exploration of absorbent itself is not enough, but also need matrix material to support. Based on this circumstance, the study summarises various kinds of polymer-based nanocomposites used as excellent absorbers for practical MA applications.