High energy ball mill was performed on fly ash through planetary by different grinding time. Particle size of fly ash was measured. The results showed that the powder began to reunite after 10 hours of grinding. Two different grinding methods were used on fly ash, and silica was extracted. The purity of the products was measured. The results showed that the activation effect of the mix grinding was better than separate grinding; After grinding more than 10 hours, the increment of the activation by increasing the time was slow, and the efficiency of mechanical activation decreased.