By applying the high-order perturbation formulas based on the cluster approach for the EPR parameters of 3d2 ions in trigonal symmetry, the zero-field splitting D, g factors gparallel, gperpendicular, and hyperfine structure constants Aparallel, Aperpendicular for Ti2+ and V3+ ions in CdS crystals are studied. From the studies, the defect structures of these paramagnetic impurity centers are obtained and the EPR parameters are also explained reasonably.