In this paper, we have investigated the electronic structure and magnetic properties of K and Mn co-doped BaCd 2 As 2 using density functional theory within the generalized gradient approximation ( GGA ) + U schemes. Calculations show that the ground state magnetic structure of Mn -doped BaCd 2 As 2 is antiferromagnetic while K and Mn co-doped BaCd 2 As 2 is ferromagnetic. Electronic structures indicate that the superexchange mechanism leads to the antiferromagnetic coupling between Mn atoms in Mn -doped BaCd 2 As 2 while the hole-mediated Zener's p–d exchange mechanism leads to the ferromagnetic coupling between Mn atoms in K and Mn co-doped BaCd 2 As 2.