By means of the complete energy matrix diagonalization procedure of 3d2/3d8 ions in trigonal symmetry and using the superposition model, the electron paramagnetic resonance (EPR) parameters for Ni2+ ions in RbMgF3 crystals with C3v and D3d symmetry are studied. From the investigation, the defect structures of these paramagnetic impurity centers are obtained and the EPR parameters are explained reasonably. - PACS numbers: 76.30.Fc, 61.72.Bb, 71.70.Ch