Based on the 252 x 252 complete energy matrices for a d(5) configuration ion in tetragonal ligand-field, the relationship between the defect structure and the EPR parameters b(2)(0), b(4)(0) has been investigated. From our calculation, the local structure around impurity ion has been determined. Meanwhile, the temperature influence which varies with the kinds of doping ions on distortion has been discussed and the change curves of the zero-field splitting energies Delta E-1, Delta E-2 as functions of the local structure distortion parameter Delta R for TiO2: Fe3+ and TiO2: Mn2+ systems have been plotted. (c) 2008 Elsevier B. V. All rights reserved.