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We conducted a study on Mn doping in 67Pb (Mg${}_{1∕3}$Nb${}_{2∕3}$)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 $1260^{\circ }$C. Experimental analysis of electrical properties was performed within the temperature range of $-80$–$200^{\circ }$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 $Q_m$ factor (510) and the reduced dielectric loss tan $\delta$ 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 $Q_m$ and tan $\delta$ are enhanced to about 1200, 0.87 up to 1.5wt.% MnO₂, and then, $Q_m$ decreases to 510, but tan $\delta$ increases to 3.78% for 5 wt.% MnO₂. The machinal $Q_m$ 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.