We investigated the complementary effects of TiO2 and MoO3 additives on the magnetic properties, the core loss, and the dielectric properties of MnZn ferrites. We analyzed the composition factors influencing the permeability of MnZn ferrites. A high initial permeability base ZnO-MnO-Fe2O3 composition ratio was selected. Electrical and dielectric analyses indicated that the introduction of TiO2 can improve the high-frequency loss properties of MnZn ferrite cores, but such introduction will also have a negative effect on the magnetic properties of the sintered samples. Introduction of MoO3 can alleviate the negative influence of TiO2 and also reduce the internal polarization intensity. As a result, the dielectric constant and corresponding dielectric loss may be reduced. We give experimental results in the paper.