Dense Mn1.1Co1.5Fe0.4O4 ceramics are successfully synthesized by using micron- and nano-sized particles as raw materials in a solid-state reaction method. The results show that the grain sizes of the as-sintered ceramics decreased with the increasing amounts of nano-sized particles. Interestingly, the grain surface presents concave flakes when all nano-sized particles are used. In particular, the resistance of the grain boundaries and the migration of oxygen vacancies increased the resistivity and aging coefficient, respectively. This study indicates that it's a useful approach to modulate the structural and electrical properties by using the different particle sizes of raw materials.