We have systematically investigated the electronic and magnetic properties of hypothesized A‐site‐ordered perovskite YMn3Sc4O12 using first‐principle calculation based on the density functional theory. Our calculated results predict that YMn3Sc4O12 is both thermodynamically and mechanically stable and its ground state is antiferromagnetic insulator. The Mn3+ is in the high‐spin state. More importantly, by comparison to YMn3Al4O12, we point out that the empty Sc 3d orbital provides the MnOScOMn superexchange interaction, which is similar to its isostructural perovskite CaCu3Ti4O12, and enhances the antiferromagnetic interaction between Mn ions. From these calculations, we can clearly see that the empty 3d orbital plays an important role to realize superexchange interaction. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011