The strengthening effects of alloying elements Re, Ta, and W in the [110] (001) dislocation core of the γ / γ′ interface are studied by first-principles calculations. From the level of energy the substitution formation energies and the migration energies of alloying elements are computed and from the level of electron the differential charge density (DCD) and the partial density of states (PDOSs) are computed. Alloying elements above are found to tend to substitute for Al sites γ′ phase by analyzing the substitution formation energy. The calculation results for the migration energies of alloying elements indicate that the stability of the [110] (001) dislocation core is enhanced by adding Ta, W, and Re and the strengthening effect of Re is the strongest. Our results agree with the relevant experiments. The electronic structure analysis indicates that the electronic interaction between Re-nearest neighbor (NN) Ni is the strongest. The reason why the doped atoms have different strengthening effects in the [110] (001) dislocation core is explained at the level of electron.