The intrinsic conduction mechanism and optimal sintering atmosphere of (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 (BCZT) ceramics was regulated by doping Mn element in this work. By Hall and impedance analysis, the undoped BCZT ceramics exhibit a typical n–type conduction mechanism, and the electron concentration decreases with the increasing oxygen partial pressure. Therefore, the undoped ceramics exhibit best electrical properties (d33 = 585 pC/N, kp = 56%) in O2. A handful of Mn doping element would transfer the conduction mechanism from n-type into p–type. And the hole concentration reduces with the decreasing oxygen partial pressure for Mn-doped BCZT ceramics. Therefore, the Mn-doped ceramics sintered in N2 have the highest insulation resistance and best piezoelectric properties (d33 = 505 pC/N, kp = 50%). The experimental results demonstrate that the doping Mn element can effectively adjusts the intrinsic conduction mechanism and then predicts the optimal atmosphere.