The invention belongs to the technical field of high-duty refractory for electric furnace and converter linings and ladle linings and in particular relates to an unburned magnesia-carbon brick and a preparation method thereof. The unburned magnesia-carbon brick is characterized by comprising the following components in parts by weight: 80-90 parts of fused magnesite (more than or equal to 97% of MgO, the granularity of 0.1-5mm and the moisture content of less than or equal to 4%), 12-16 parts of graphite (more than or equal to 98% of C, the granularity of less than or equal to 400 meshes, and the moisture content of less than or equal to 0.15%), 0.5-1.5 parts of metal aluminum powder (more than or equal to 98% of Al and the granularity of less than or equal to 400 meshes), 1-3 parts of an aluminum magnesium alloy (more than or equal to 98% of Al+Mg and the granularity of less than or equal to 400 meshes), 0.2-0.8 part of boron carbide (more than or equal to 99% of BC4 and the granularity of 200-325 meshes), 1-2.5 parts of high temperature pitch (softening temperature of more than or equal to 150 DEG C, more than or equal to 50% of residual carbon and the granularity of 100-200 meshes), 0.2-0.5 part of a rare earth oxide (the granularity of 300-350 meshes), 3-5 parts of ceramic bond, 3-4 parts of a complex magnesium-aluminum cementing agent and 1-3 parts of water. The unburned magnesia-carbon brick disclosed by the invention has the advantages of simple and safe preparation method, low cost, no need of high-temperature firing, high density, high strength, high corrosion resistance, molten metal resistance, high oxidation resistance, energy conservation and emission reduction and the like.