The nanocomposites consisting of α-Fe and a small quantity of Nd2Fe14B have been prepared using rapid quenching from Nd6Fe91B3 melt with low rare earth content and ball milling for 25 h. The effect of rapid quenching speed on the phase composition, microstructure, and microwave electromagnetic properties of α-Fe/Nd2Fe14B nanocomposites have been investigated. Results show that the microwave complex permeability increases and the resonance frequencies (fr) of as-spun Nd6Fe91B3 alloys shifts to lower values with the increase of quenching speed, due to the decrease of Nd2Fe14B with the large anisotropy field (HA). The real part of complex permeability of Nd6Fe91B3 alloy reaches the maximum μmax′=7.88 at 1.55 GHz and imaginary part of permeability reach the maximum at 4.17 GHz μmax″=4.66. Furthermore, the α-Fe/Nd2Fe14B nanocomposites with low Re content shows an excellent microwave permittivity, and its resonance appears at about 2 GHz. Therefore, the α-Fe/Nd2Fe14B nanocomposites are beneficial to be applied to electromagnetic wave absorber in GHz, due to the cooperation effect of magnetic loss and dielectric loss.