The invention discloses a method for preparing manganese carbide by gas-based reduction of manganese oxides. The method comprises the following steps of mixing the manganese oxides, a bonding agent and water uniformly, agglomerating and drying, putting dry blocks into mixed atmosphere containing H2, CH4, CO and N2, calcining to obtain a manganese carbide product. Compared with the traditional method for preparing the manganese carbide by high-temperature smelting of manganese metal and graphite, the method disclosed by the invention has the characteristics of moderate reaction condition, low cost and simple process flow, and the prepared manganese carbide is high in purity and is applicable to requirements for preparing precursors of various functional materials.