The invention relates to the technical field of preparation of cement raw materials and in particular relates to a preparation method of silicon beads with high hydration activity. According to the method provided by the invention, sodium silicate hydrate in sodium silicate alkali dreg is transformed into sodium carbonate and silicon dioxide; silicon dioxide is ultrafine powder and directly reactswith a gas phase; the crystallization degree is relatively low and the reaction activity is relatively high; original silicon dioxide in the sodium silicate alkali dreg is a product obtained by quenching at 1300 to 1500 DEG C; high-temperature gas is decomposed into water and oxygen through hydrogen peroxide in a polycrystalline silicon powder raw material at the same time, and concrete is not expanded any more; the reaction activity of the polycrystalline silicon waste material is improved through local oxidization in the high-temperature gas. The granularity of the ground sodium silicate alkali dreg is mainly in a range of 10 to 30 mu m, and the granularity of the polycrystalline silicon waste material is mainly in a range of 1 to 3mu m; the ground sodium silicate alkali dreg and the polycrystalline silicon waste material are matched, so that final grain size gradation of a product is optimized and the performance of the silicon beads with high hydration activity is improved.