In this work, first-principles density functional theory was applied to investigate the effect of Co-doping on the stability of γ′ -Ni3Al. The optimal parameters were determined by comparing the simulations and experimental results. Based on the plane wave pseudopotential method, the crystal structure, total energy, formation enthalpy, cohesive energy, electronic density of states and electron density difference of γ′-Ni3Al phases were calculated, which was used to analyze the stability and bonding characteristics of the crystal structure. The calculation results indicate that the structure of unit cell is more stable after the Al atom is replaced by Co atom. In the range from -10 eV to Fermi energy, the orbital hybridization among Co (Ni) 3d electrons and Al s, p electrons occurs, and the charge transfer among atoms increases obviously, which enhances the covalent bonding in doped γ′ phases. When the Co atom replaces the Al atom instead of the Ni atom, the number of bonding electrons increases at low Fermi energy, and surrounding valence electron interactions are enhanced, so the stability γ′ -Ni3Al phase will be improved. Finally, the simulation results were confirmed by long time aging heat treatment experiments of Inconel 718 alloy.