Development of Fe-based superalloys is highly demanded for both scientific interests and broad applications. Generally, the mechanical properties of traditional alloys strengthened by carbides and Laves phase, etc., are degraded after long-term operation at HTs (> 923 K) due to microstructural instability. Considering that the superiority of Ni-based superalloys benefits from their unique coherent microstructure, the coherent precipitation of cuboidal B2 nanoparticles will certainly improve the HT microstructure and mechanical properties of Fe-based superalloys. In the present work, we developed a new Fe-based superalloy with cuboidal B2-NiAl nanoparticles coherently-precipitated into BCC matrix, which has not been reported. This alloy exhibits an excellent microstructural stability at 973 K with a slow particle coarsening rate, which is ascribed to the moderate lattice misfit (0.24 ~ 0.67 %) between BCC/B2. Also, it is the cuboidal B2 nanoprecipitation that renders the current alloy with high yield strength (238 ~ 258 MPa) at 973 K.