In order to meet the continuous progress of the mechanical properties of aeroengine hot-end components， the effects of Re on the mechanical strength of Ni₃Al intermetallics are investigated by the first-principles calculation based on density functional theory. By establishing the slip model and fracture model of Ni₃Al before and after doping Re， unstable stacking fault energy γUS and fracture energy γC are calculated， and then the effects of Re on the yield strength and fracture strength of Ni₃Al are determined. In addition， according to empirical criteria， the γC/γUS value can characterize the toughness or brittleness of materials. The results show that Re augments γUS in the two slip systems [112](111) and [11ˉ0](111) of Ni₃Al， indicating Re makes them difficult to move. Thus Re makes Ni₃Al difficult to perform the plastic deformation and enhances its yield strength. Furthermore， Re augments γC at the close-packed surface of Ni₃Al， making it difficult to fracture at the surface and enhancing its fracture strength. Regarding to improving the toughness of Ni₃Al， Re has different effects in the different slip directions at the close-packed surface. The research can provide the theoretical basis for improving the mechanical properties of single crystal blades of aeroengines.