The invention relates to a soaking-salt sintered magnesium aluminate spinel brick for an RH furnace. Physicochemical indexes of the soaking-salt sintered magnesium aluminate spinel brick are as follows: MgO is larger than or equal to 86 percent, Al2O3 is larger than or equal to 10 percent, SiO2 is smaller than or equal to 0.74 percent, the compressive strength is larger than or equal to 108.4MPa, the apparent porosity is smaller than or equal to 13.0, the volume density is larger than or equal to 3.03g/cm<3>, and the water cooling and thermal shock stability at the temperature of 1100 DEG C is larger than or equal to 13. The soaking-salt sintered magnesium aluminate spinel brick is prepared from the following raw materials in parts by weight: 20-35 parts of 200-mesh 97 high-purity magnesia, 15-25 parts of 0-1mm 97 high-purity magnesia, 10-15 parts of 1-3mm 97 high-purity magnesia, 10-15 parts of 0-1mm 97 fused magnesia, 10-15 parts of 1-3mm 97 fused magnesia, 10-15 parts of 1-3mm 97 fused magnesium aluminate spinel, 3-5 parts of calcined Al2O3 micropowder and 3-5 parts of a binder paper pulp. After being sintered, the soaking-salt sintered magnesium aluminate spinel brick for the RH furnace is subjected to vacuum soaking-salt with an industrial salt solution, so that the porosity of the magnesium aluminate spinel brick is improved, and the problem of slag corrosion of an RH vacuum refining furnace is solved.