Zirconate-based dielectric ceramics are potential materials for base metal electrodes multilayer ceramic capacitors (BME-MLCCs) due to the exceptional chemical and thermal stability, as well as excellent dielectric properties. In this work, (Sr_0.7Ca_0.3)_1.02(Zr_0.95-xTi_0.05Mn_x)O_3+δ (SCZTM, 0 ≤ x ≤ 0.05) ceramics with two coexisting phases were prepared using solid-state reaction method in reducing atmosphere. This study investigates the impact of Mn doping on sintering temperature, microstructure, electric and electrical properties of SCZTM ceramics. The doping of Mn can reduce sintering temperature from 1450 ℃ to 1300 ℃. The impact of Mn doping on structure and phonon vibration is minimal, resulting in a negligible effect on intrinsic loss. The valence states of Mn ions and defects are characterized by X-ray photoelectron spectroscopy (XPS) and thermal stimulated depolarization current (TSDC). The results demonstrate the significant role of Mn doping in non-intrinsic loss. Due to the decrease in concentrate of oxygen vacancies ( ), the SCZTM (x = 0.01) ceramics exhibit attractive properties: ρ = 8.93 × 10¹⁴ Ω·cm, ε_r = 36.16, tan δ = 2.43 × 10^-4, τ_ε = 15.44 ppm/˚C (@-55~200 ℃, 1 MHz), and Q×f = 30,257 GHz (@6.12 GHz), τ_f = -9.9 ppm/℃. The SCZTM (x = 0.01) ceramic powders have been used to successfully fabricate Ni-based MLCCs with high insulation resistance of IR ≥ 39.6 TΩ, ultra-low dielectric loss of tan δ = 0.2 × 10^-4 and wide operating temperature range (Tcc = 10.88 ppm/˚C, @-55~200 ℃, 1MHz). SCZTM ceramics exhibit properties that make them suitable for use as BME-MLCCs materials with potential market applications.