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Based on the first principles of density functional theory, the factors for the difference of γ' phase distribution in the precipitation strengthening of W and Mo doped nickel base superalloy were studied. The system model of γ' - Ni3 ( Al3/8 Ti5/8 ) phase was established by VASP software, and the substitution energies of W and Mo atoms in different positions were calculated by selecting different array points in non - equivalent positions, and the occupying tendencies of W and Mo atoms in γ' phase were analyzed. The adsorption energy of the interface before and after doping W and Mo atoms were calculated, and the influences of doping W and Mo on the phase boundary were studied. The diffusion paths and potential barriers of Wand Mo atoms from γ to γ' were also calculated. The results show that the doping of W or Mo preferentially replaces No. 5 Al atom in γ' - Ni3 ( Al3/8 Ti5/8 ) phase and improves the stability of the phase boundary. The difference in allocation is caused by the fact that W replacing Al atom in the γ' phase is more likely to form vacancies than Mo, while Ni atoms in the y phase are more difficult to form vacancies and require more energy for reverse diffusion. [ABSTRACT FROM AUTHOR]