The invention relates to an alkaline composite refractory brick, which consists of a periclase-magnesium aluminate spinel flame retardant coating and a periclase-forsterite thermal-protective coating. The proportion of the alkaline composite refractory brick is as follows: 1) the proportion of the flame retardant coating is as follows: 29 to 48 percent of magnesite of between 5 and 1 millimeter, 7 to 16 percent of the magnesium aluminate spinel of between 3 and 1 millimeter, 6 to 20 percent of the magnesite of between 1 and 0.088 millimeter, 0 to 4 percent of desilicated zirconia granules of between 0.4 and 0.088 millimeter, 16 to 25 percent of the magnesite of less than 0.088 millimeter, 0 to 10 percent of magnesite micropowder of less than 0.020 millimeter, 0 to 5 percent of desilicated zirconia micropowder of less than 0.020 millimeter, 0 to 3 percent of calcium carbonate micropowder less than 0.020 millimeter, 0 to 6 percent of lanthanum oxide of less than 0.020 millimeter, and 0 to 0.3 percent of additional water reducing agent (sulfonated naphthaldehyde polymer, sulfonated melamine polymer and polycarboxylic acid or sodium salt thereof); and 2) the proportion of the thermal-protective coating is as follows: 0 to 20 percent of the magnesite of between 3.2 and 1.0 millimeter, 35 to 45 percent of the forsterite of between 3.2 and 1.0 meter, 5 to 15 percent of the magnesite of between 1.0 and 0.088 millimeter, 5 to 15 percent of the forsterite of between 1.0 and 0.088 millimeter, and 30 to 40 percent of grinding powder of the magnesite and the forsterite of less than 0.088 millimeter. The material has the advantages that the material improves the erosion resistance of the flame retardant coating by micropowder technology, and allows the sintering temperature of the flame retardant coating to be matched with that of the thermal-protective coating, thereby producing the periclase-magnesium aluminate spinel alkaline composite refractory brick which has excellent.