The invention discloses a novel electromagnetic wave absorption material and a preparation method thereof. The electromagnetic wave absorption material is an Mn-Sb alloy compound, and the general chemical formula is MnxSb or (Mn, T)xSb, wherein x is larger than 0.8 and is smaller than 1.4, and T is one or an arbitrary combination of Zr, Cr, Cu, V, Si, Zn, C, B, Al and Cd. The preparation method ofthe material comprises the steps of carrying out mixed smelting or rapid-setting ingot casting on Mn and Sb elements of which the atomic proportion of Mn to Sb or (Mn, T) to Sb is 0.8 to 1.4, so as to obtain an alloy of an NiAs hexagonal structure; and then, crushing the alloy into submicron particles capable of being utilized as an electromagnetic wave absorbent. The novel electromagnetic wave absorption material has an excellent absorption capacity for electromagnetic waves of which the frequency band is from 1 G to 100 G, the absorption capacity is high, and the working frequency band is wide; and besides, the frequency band position can be adjusted according to the utilization condition, and the electromagnetic wave absorption requirement in civil and military fields can be effectively met.