The phase stability, site preference and mechanical properties of ThMn 12 type rare-earth intermetallic compound R(Co, T) 12 (R=Er or Dy, T=V, Ti, Cr, Mo, Mn, Nb, Ni, Cu) are studied via interatomic pair potentials based on Chen’s lattice inversion technique. The results show that the ternary elements can decrease the internal energy and stabilize the ThMn 12 structure. The calculations also show that the internal energy is the lowest when the ternary elements occupy the symmetrical 8 i site. All of those are in good agreement with the experimental lattice parameters and X-ray diffraction data. The results indicate that the converted pair potentials are valid for studying the structural properties of certain kinds of complex-structured materials.