Abstract: In the ZrO₂-based ceramic systems doped with different oxides (Y₂O₃, MgO and Al₂O₃), the behaviors of electronic and ionic conductivity have been investigated by the quantum chemical SCF-Xα-SW method. The results of the electronic energy spectra and local state density of atoms show that, for the ZrO₂ system doped with Al₂O₃, the energy gap near the Fermi energy level becomes smaller, which implies that the electronic conductivity increases. Since the binding energy between Al and O atoms is increased, the energy for oxygen vacancy migrating is enhanced and the ionic conductivity decreases. In the M_xO_y-doped ZrO₂ systems, due to the doping effect of Al₂O₃, MgO and Y₂O₃, the ionic conductivity increases successively, and the electronic conductivity decreases successively. The calculation results are in agreement with that of references and experience.