In nanosystems, the metallic nanowires are subjected to significant and cyclic bending deformation upon being integrated into stretchable and flexible nanoelectronic devices. The reliability and service life of these nanodevices depend fundamentally on the bending mechanical properties of the metallic nanowires that serve as the critical components. An in-depth understanding of the deformation behavior of the metallic nanowires under bending is not only essential but also imperative for designing and manufacturing high-performance nanodevices. To explore the mechanism of the bending plasticity of the metallic nanowire, the bending deformations of B2-FeAl alloy nanowires with various crystallographic orientations, sizes and cross-sectional shapes are investigated by using molecular dynamics simulation. The results show that the bending behavior of the B2-FeAl alloy nanowires is dependent on neither their size nor cross-sectional shape of the nanowire, but it is highly sensitive to its axial orientation. Specifically, both $\left\langle {111} \right\rangle $- and $\left\langle {110} \right\rangle $-oriented nanowires are generated through dislocation nucleation during bending, with the $\left\langle {111} \right\rangle $-oriented nanowires failling shortly after yielding due to brittle fracture, while the $\left\langle {110} \right\rangle $-oriented nanowires exhibit good ductility due to uniform plastic flow caused by continuous nucleation and stable motion of dislocations. Unlike the aforementioned two nanowires, the bending plasticity of the $\left\langle {001} \right\rangle $-oriented nanowire is mediated by the stress-induced transition from B2 phase to L1₀ phase, which leads to excellent ductility and higher fracture strain. The orientation dependence of bending deformation can be understood by considering the Schmid factor. Moreover, the plastically bent nanowires with $\left\langle {110} \right\rangle $ and $\left\langle {001} \right\rangle $ orientation are able to recover to their original shape upon unloading, particularly, the plastic deformation in the $\left\langle {001} \right\rangle $-oriented nanowire is recoverable completely via reverse transformation from L1₀ to B2 structures, exhibiting superelasticity. This work elucidates the deformation mechanism of the B2-FeAl alloy nanowires subjected to bending loads, which provides a crucial insight for designing and optimizing flexible and stretchable nanodevices based on metallic nanowires.