Abstract: This is an article in the field of mineral processing engineering. According to the principle of mechanochemistry, the water-quenched silico-manganese slag is ground by vibrating mill. The effect of grinding time on the specific surface area, particle size distribution and activity evaluation of the water-quenched silico-manganese slag is studied, and the specific surface area is used. The specific surface area, particle size distribution, phase analysis and particle morphology of water-quenched silico-manganese slag powder were discussed with laser particle size analyzer, XRD and SEM and other characterization methods. At the same time, the water with different grinding time was also studied. Effect of silicomanganese slag powder as admixture on the compressive strength of geopolymers. The results show that with the extension of the grinding time, the particle size distribution of the silicomanganese slag gradually shifts to the left, the particle size is gradually refined, and the quartz phase gradually changes to an amorphous structure. From the perspective of cost, when the grinding time is 25 min and the specific surface area is 1.8281 m²/g as fly ash geopolymer admixture, the 28 d compressive strength can reach 26.79 MPa. And it is determined that the difficult-to-wear phase is the orthomanganese pyroxene crystal structure, and different manganese-containing phases.