Abstract: The Griffith fracture work and generalized stacking fault energy of γ-Al/γ’-Al₃ Sc（Er） phase boundary and the variation of Griffith fracture work and generalized stacking fault energy of γ-Al/γ’-Al₃ Sc under different Er segregation were studied by the first-principles calculation method. The results show that the shear resistance of the γ-Al/γ’-Al₃ Sc phase boundary is better than that of the γ-Al/γ’-Al₃ Er phase boundary, while the tensile resistance of the γ-Al/γ’-Al₃ Er phase boundary is better than that of the γ-Al/γ’-Al₃ Sc phase boundary. With the increase of Er segregation in the γ-Al/γ’-Al₃ Sc phase boundary structure, the Griffith fracture work and generalized stacking fault energy of the phase boundary are greatly improved. Further calculation of the ratio of Griffith fracture work to generalized stacking fault energy（G/B） shows that the segregation of Er increases the fracture work and shear strength of the γ-Al/γ’-Al₃ Sc phase boundary. The γ-Al/γ’-Al₃ Sc phase boundary with different orientations exhibits intrinsic brittleness, and the segregation of Er does not change the ductile-brittle properties of the phase boundary. The study can provide a reference for the regulation of phase boundary properties of Al-Sc alloys and the composition and structure design of high-performance and low-cost rare earth aluminum alloys.