Microstructure of solid-phase reduction on manganese oxide ore fines containing coal (MOOFCC) is one of important kinetics conditions of influencing microwave heating. In the condition that an atomic molar ratio of rO: rC in MOOFCC is 1:1.06 as well as a molecular molar ratio of rSiO2: rCaO is 1:1.28, 1 kg of MOOFCC is heated by microwave to reach 1000～1300℃ and hold different time respectively. Experiments show that the metal phase takes the iron-based metal compounds containing manganese as the main content. The manganese content of metal phase increases with the rise of temperature. The partical size of the metal phase is within the range from 0.01 to 0.05mm. MO2 phase in the stuff is entirely changed into MnO phase and the slag phase is mainly composed of wollastonite and manganese olivine. The stuff reduced is loose and massive as a whole with porosity of it from 30 to 45 %. The low softening-melting property and the low density of the stuff impact, to some degree, the solid-phase reduction of powder by microwave heating.