High-strength mullite castables are refractory castables mainly made of mullite as the principal crystalline phase. They have strong thermal shock resistance, small thermal expansion coefficient, low thermal conductivity, and chemical resistance. They are often used in various high temperatures. The door lining materials of the kiln, such as the calciner door, heating furnace door, coke oven door, etc., are also used in the front and rear kiln mouths of cement kilns, coolers, coal injection pipes and other high-temperature wear-resistant parts.