The structural, elastic, electronic and bonding nature and vibrational properties of UAI in B2 structure under zero pressure have been investigated by performing first principles calculations using density functional theory. The exchange-correlation potentials were treated within the generalized gradient approximation (GGA). The calculated quantities are agreed well with the available results. The electronic properties such as band structure and density of states reveal that UAI is metallic in nature with large overlap at Fermi level. The single-crystal elastic stiffness constants of UAI are investigated using stress-strain method. Present results for elastic constants show that this compound is mechanically metastable which is agreement with previous study . The chemical bonding is interpreted by calculating the density of states and electron density distribution analysis. UAI has metallic bonding characteristic. The presented phonon dispersion curves and one-phonon DOS is also confirmed that this compound is dynamically unstable.