Active а-Al2O3 Micropowder is calcined in a unique firing process by using excellent alumina as its raw material, selected composite mineralizing agents, and adopted superfine grinding technology. It has good properties such as, high inversion rate, good activity, small water demand, good fluidness, high bulk density, excellent thermal strength etc. It is an excellent filling agent and superfine powder coagulation binder for producing monolithic refractories. The product has been used in numerous famous manufacturers, and has gained good reputations.