The Mn-Zn ferrite powders prepared by high energy ball milling were heat-treated, subsequently compacted and sintered by spark plasma sintering (SPS). Based on the observation of microstructure, the characteristics of samples after SPS were investigated and compared with ones after conventional sintering. The size of initial powders was approximately 650 nm and decreased to 230 nm after milling at 300 rpm for 3 h. After heat treatment at 973K for 1h, the milled powders became larger to approximately 550 nm in size again and the peaks of Mn2O3 disappeared in XRD patterns. In the samples after SPS, the Fe2O3 and MnZnFe2O4 phases decomposed at the higher temperatures than 1173K and 1373K, respectively, while only MnZnFe2O4 phase was detected in the samples conventionally sintered at 1273~1673K. As the sintering temperature increased, the relative density after SPS increased more quickly than that after conventional sintering. In particular, it reached approximately 99% after SPS at 1473K.