[en] Highlights: • Site preference of TMs on B2 CuDy-based compounds is studied. • Alloying effects on mechanical properties are discussed. • Elastic anisotropic properties are discussed by 2D and 3D figure. • Electron structures are calculated to discuss the mechanical behavior. Ab initio calculations have been performed to predict the site preference and mechanical behavior of transition-metal elements in B2 DyCu alloy. The formation enthalpy of these ternary alloys indicates that the majority of the transition metal elements tend to replace a Cu site and form Dy₈Cu₇M intermetallics. According to the calculated results of mechanical modulus of each compound, Dy₇Cu₈V possesses the highest ductility and Dy₇Cu₈Hf etc. have the higher shear modulus and Young's modulus. The anisotropic factors, 3D and 2D directional Young's modulus predict DyCuM compounds are all anisotropic materials, but the degree of anisotropy is very small. In addition, the electronic densities of states and electron density difference explain the electron properties of DyCuM compounds and further discuss their structural stability and mechanical behavior.