The work aims to prepare the Fe-based alloy containing nano-NiAl phase with B2 structure by mechanical alloying and hot-press sintering and then study the effects of different nano-NiAl contents (30%, 40%, 50%, and 60%) on the microstructure and mechanical property of alloy. Ni powder and Al powder were used as raw materials to prepare B2 nano-NiAl powder by high-energy ball milling. The NiAl powder and Fe powder were mixed and sintered by vacuum hot-pressing sintering furnace to obtain the block sample. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to observe microstructure and analyze phases. Hardness, density, compressive strength and oxidation resistance (600 ℃) of Fe-based alloys with different contents of NiAl were tested. Hardness and compressive strength of alloy increased firstly, and then decreased with NiAl content. When NiAl content was 50wt.%, hardness and compressive strength of alloy were 35.2 HRC and 2,530 MPa respectively and the density was 6.68 g/cm3. The compressive strength of the alloy increased by 239.6% and the density decreased by 14.5% when compared with those of alloy not added with NiAl. When θ=600 ℃ and t=1200 min, the surface oxidation weight gain was reduced by 37.9% compared with that of pure iron. NiAl phase size was about 100~200 nm and the phase had the most uniform structure and the highest density. Nano-NiAl with B2 structure can effectively reduce the density of iron-based alloy and improve the mechanical properties. However, the mechanical properties of the alloy are greatly reduced, when NiAl content is too high, since nano-NiAl phase with B2 structure is a hard and brittle phase.