Abstract: Tobermorite (TOB) was a major phase of calcium silicate board and autoclaved aerated concrete, which was widely used refractory materials and thermal insulation materials in the field of civil engineering . However, these materials were easy to wear so that a large number of solid wastes have been produced. The problem of functionalized utilization of TOB needed to be resolved urgently. In the present paper, TOB samples with good crystal morphology were prepared by hydrothermal synthesis and were calcined at different temperatures (H-TOB). Then the porous SiO₂ material (AH-TOB) was successfully prepared by acid treatment of H-TOB, and AH-TOB material was characterized by XRD, N₂ adsorption-desorption, SEM, TEM and other testing methods to investigate the formation mechanism. The results of BET and pore size distribution test analysis showed that the specific surface area of 300AH-TOB after thermal activation at 300 ℃ and hydrochloric acid modification was 570.25 m²/g, and the total pore volume was 0.747 m³/g. After heat treatment and hydrochloric acid treatment, the calcium ions in TOB were selectively dissolved, and the main component of the acid-insoluble material was silica. Therefore, it was inferred that the silicon oxide exhibited an eight-membered ring double-chain deformation structure composed of a silicon-oxygen tetrahedron, resulting in an increase in mesopores and micropores. The adsorption performances of TOB, 300H-TOB and 300AH-TOB on two organic dyes, Safranine T (ST) and crystal violet (CV）, were investigated by static adsorption experiments. When the mass of adsorbent was added at 0.4 g, the adsorption rates of ST and CV were 56.35% and 47.69% on TOB; 25.57% and 42.69% on 300H-TOB; and 91.46% and 88.86% on 300AH-TOB, respectively. The porous material prepared from TOB had favorable adsorption of organic dyes, indicating its promising potential in adsorption application.