We conducted a study on Mn doping in 67Pb (Mg1∕3Nb2∕3)O₃-33PbTiO₃(67PMN-33PT), which is a ferroelectric material exhibiting a morphotropic phase boundary (MPB). The samples were doped with MnO₂ at mass ratios ranging from 0.5 to 5.0wt.% and subsequently sintered at temperatures ranging from 1200 to 1260°C. Experimental analysis of electrical properties was performed within the temperature range of ?80–200°C. Electron paramagnetic resonance (EPR) testing was conducted on these samples to investigate Mn solubility in PMN-PT ceramics and their existence in different valence states. The results indicate that at a doping ratio of 0.5wt.% and sintering temperature of 1220–1240^°C, Mn ions achieved a homogeneous dispersion within the crystal lattice, leading to the enhanced electromechanical Qm factor (510) and the reduced dielectric loss tan δ to minimum (0.30%) compared to the no doping Mn, however, as the Mn ions dopant content increase higher than 1.0wt.% and sintering temperatures 1200–1260^°, the unexpected results have been observed that both Qm and tan δ are enhanced to about 1200, 0.87 up to 1.5wt.% MnO₂, and then, Qm decreases to 510, but tan δ increases to 3.78% for 5 wt.% MnO₂. The machinal Qm and dielectric loss can be understood by the (Mn-Vo) defect dipoles in lattice, domain wall and grain-bounary, together with the increasing of the MnO₂, Mn₂O₃ or their mixed phase of Mn₃O₄ in the grain boundary.