A theoretical method for studying the local properties about Ni2+ ion in a trigonal ligand-field has been proposed by diagonalizing the complete energy matrix and considering the electron paramagnetic resonance (EPR) parameters D and g. For nickel-doped ZnSiF6 center dot 6H(2)O and ZnSiF6 center dot 6D(2)O systems, the local lattice distortion and local angular thermal expansion coefficient have been investigated at various temperatures. The calculated results indicate that the local structure around octahedral Ni2+ centre has a compression distortion in the two systems. Moreover, the temperature dependence of the local angular thermal expansion coefficient has also been analysed. (C) 2008 Elsevier B.V. All rights reserved.